Low-temperature liquid pipeline transient simulation method and system considering phase change
By considering the phase transition, the problem that traditional models cannot simulate gas-liquid temperature stratification is solved by calculating the gas-phase fraction and physical phase state, and combining the gas-phase and liquid phase physical properties parameters, the problem that traditional models cannot simulate gas-liquid temperature stratification is achieved, and the accurate simulation of low-temperature liquid pipelines is achieved.
Patent Information
- Application Number
- CN202510548301.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-08-01
AI Technical Summary
The traditional two-phase flow model cannot simulate the gas-liquid temperature stratification, resulting in insufficient accuracy of the gas-liquid two-phase flow during operation of the low-temperature liquid pipeline.
A transient simulation method for low-temperature liquid pipelines that consider phase change is adopted. By obtaining pipeline parameters, medium and boundary conditions, the gas phase fraction and physical phase state are calculated, and the gas phase and liquid phase physical properties parameters are weighted fusion to determine the physical properties parameters of the homogeneous phase.
Accurate simulation of the two-phase flow of gas and liquid is achieved, making up for the shortcomings of traditional models, and improving the accuracy of low-temperature liquid pipeline simulation.
Smart Images
Figure CN120409344A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of phase simulation, and particularly to a transient simulation method and system for cryogenic liquid pipelines considering phase change. Background Art
[0002] The statements in this section merely provide background technical information related to the present invention and do not necessarily constitute prior art.
[0003] During the operation of cryogenic liquid pipelines, the pipeline medium is likely to enter the two-phase region due to temperature increase or pressure decrease. The cryogenic liquid vaporizes to form a gas-liquid two-phase flow. The vaporized gas accumulates in the upper part of the pipeline, making the gas temperature in the upper part of the pipeline higher than the liquid temperature in the lower part. However, traditional two-phase flow models can only simulate one-dimensional flow and assume that the temperatures of the gas and liquid phases are the same. Therefore, they cannot simulate the gas-liquid temperature stratification situation. Summary of the Invention
[0004] To solve the above problems, the present invention proposes a transient simulation method and system for cryogenic liquid pipelines considering phase change, which can accurately simulate the physical property parameters of gas-liquid two phases.
[0005] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, a transient simulation method for cryogenic liquid pipelines considering phase change is proposed, including: Obtain pipeline parameters, pipeline medium, and pipeline boundary conditions; Use the pipeline parameters, pipeline medium, and pipeline boundary conditions to determine the pressure and temperature of each cross-section of the pipeline at each time layer; Perform phase equilibrium calculations on each cross-section of the pipeline according to the temperature and pressure of each cross-section at each time layer to determine the gas phase fraction of each cross-section at each time layer; Judge the phase state of each cross-section according to the gas phase fraction; For cross-sections with a gas-liquid two-phase state, determine the top temperature of the cross-section, calculate the gas phase physical property parameters according to the top temperature of the cross-section, calculate the liquid phase physical property parameters according to the temperature of the cross-section, and perform weighted fusion on the gas phase physical property parameters and the liquid phase physical property parameters to obtain the physical property parameters of the homogeneous phase of the cross-section.
[0006] Furthermore, for cross-sections with a pure liquid phase state, calculate and determine the liquid phase physical property parameters of the cross-section according to the temperature of the cross-section, and the liquid phase physical property parameters are the physical property parameters of the homogeneous phase of the cross-section.
[0007] Furthermore, obtain the maximum value of the wave speeds of all cross-sections in the previous time layer; Determine the time step of the current time layer according to the maximum value of the wave speeds of all cross-sections in the previous time layer.
[0008] Further, for the cross-section with the gas-liquid two-phase physical state, based on the liquid-phase wave velocity and the gas-phase wave velocity of this cross-section, determine the wave velocity of the homogeneous phase of this cross-section, that is, the wave velocity of this cross-section; wherein, the wave velocity of the homogeneous phase is the square root of the sum of the squares of the liquid-phase wave velocity and the gas-phase wave velocity.
[0009] Further, when the gas-phase fraction is 0, the physical state of the cross-section is pure liquid phase; When the gas-phase fraction is 1, the physical state of the cross-section is pure gas phase; When the gas-phase fraction is greater than 0 and less than 1, the physical state of the cross-section is gas-liquid two-phase.
[0010] Further, calculate and determine the top temperature of the cross-section according to the cross-section temperature and the top temperature calculation model.
[0011] In a second aspect, a transient simulation system for cryogenic liquid pipelines considering phase change is proposed, including: A data acquisition unit for acquiring pipeline parameters, pipeline medium, and pipeline boundary conditions; A hydraulic and thermal parameter calculation unit for using the pipeline parameters, pipeline medium, and pipeline boundary conditions to determine the pressure and temperature of each cross-section of the pipeline at each time layer; A gas-phase fraction calculation unit for performing phase equilibrium calculations on each cross-section of the pipeline according to the temperature and pressure of each cross-section of the pipeline at each time layer to determine the gas-phase fraction of each cross-section of the pipeline at each time layer; A physical state judgment unit for judging the physical state of each cross-section according to the gas-phase fraction; A physical property parameter calculation unit for, for the cross-section with the gas-liquid two-phase physical state, determining the top temperature of this cross-section, calculating the gas-phase physical property parameters according to the top temperature of this cross-section, calculating the liquid-phase physical property parameters according to the temperature of this cross-section, and performing weighted fusion on the gas-phase physical property parameters and the liquid-phase physical property parameters to obtain the physical property parameters of the homogeneous phase of this cross-section.
[0012] In a third aspect, a computer device is proposed, and the device includes: A processor suitable for executing a computer program; A computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by the processor, it implements a transient simulation method for cryogenic liquid pipelines considering phase change proposed in the first aspect.
[0013] In a fourth aspect, a computer-readable storage medium is proposed, and the computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded and executed by a processor to implement a transient simulation method for cryogenic liquid pipelines considering phase change proposed in the first aspect.
[0014] In a fifth aspect, a computer program product is proposed. The computer program product includes a computer program which, when executed by a processor, implements a transient simulation method for a cryogenic liquid pipeline considering phase change proposed in the first aspect.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: For a transient simulation method and system for a cryogenic liquid pipeline considering phase change proposed by the present invention, when determining the physical property parameters of a cross-section, the gas-phase fraction of each cross-section is first calculated, and based on the gas-phase fraction, the phase state of the cross-section is determined; then, according to the phase state of the cross-section, a corresponding calculation method is selected to calculate and determine the physical property parameters of the homogeneous phase of the cross-section; among them, for a cross-section with a gas-liquid two-phase state, according to the temperature of the cross-section, the top temperature of the cross-section is determined, the gas-phase physical property parameters are calculated based on the top temperature of the cross-section, the liquid-phase physical property parameters are calculated based on the temperature of the cross-section, and the gas-phase physical property parameters and the liquid-phase physical property parameters are weighted and fused to obtain the physical property parameters of the homogeneous phase of the cross-section; the accurate determination of the physical property parameters of the homogeneous phase in the gas-liquid two-phase is realized, and the problem that the traditional two-phase flow model can only simulate one-dimensional flow is solved.
[0016] Advantages of additional aspects of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The specification drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application.
[0018] Figure 1 is a flowchart of a transient simulation method for a cryogenic liquid pipeline considering phase change proposed by the present invention; Figure 2 is a graph showing the change of the pipeline starting point pressure over time; Figure 3 is a graph showing the change of the temperatures at the top and bottom of the pipeline starting point over time; Figure 4 is a graph showing the change of the gas-phase fraction of the pipeline starting point cross-section over time; Figure 5 is a graph showing the change of the temperature of the pipeline starting point cross-section over time. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] The present invention will be further described below in conjunction with the drawings and embodiments.
[0020] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application pertains.
[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0022] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.
[0023] Embodiment 1 In order to accurately simulate the physical property parameters of a cryogenic liquid pipeline, in this embodiment, a transient simulation method for a cryogenic liquid pipeline considering phase change is disclosed, including: Obtain pipeline parameters, pipeline medium, and pipeline boundary conditions; Utilize the pipeline parameters, pipeline medium, and pipeline boundary conditions to determine the pressure and temperature of each cross-section of the pipeline at each time layer; According to the temperature and pressure of each cross-section of the pipeline at each time layer, perform phase equilibrium calculations on each cross-section of the pipeline to determine the gas phase fraction of each cross-section of the pipeline at each time layer; Judge the phase state of each cross-section according to the gas phase fraction; For the cross-sections with a gas-liquid two-phase state, determine the top temperature of the cross-section, calculate the gas phase physical property parameters according to the top temperature of the cross-section, calculate the liquid phase physical property parameters according to the temperature of the cross-section, and perform weighted fusion on the gas phase physical property parameters and the liquid phase physical property parameters to obtain the physical property parameters of the homogeneous phase of the cross-section.
[0024] Among them, the pipeline parameters include pipe length, number of segments, pipeline inner diameter, pipeline wall thickness, pipeline inner surface roughness, pipeline total heat transfer coefficient, ambient temperature of the pipeline, initial pressure and initial temperature of the fluid in the pipe.
[0025] Taking the pipeline medium as pure CO2 as an example, a transient simulation method for a cryogenic liquid pipeline considering phase change disclosed in this embodiment is described in detail.
[0026] In this specific embodiment, the pipeline medium is pure CO2; The pipeline parameters include a pipe length of 22 m, a number of segments of 10, a pipeline inner diameter of 187 mm, a pipeline wall thickness of 16 mm, a pipeline inner surface roughness of 0.045 mm, a pipeline total heat transfer coefficient of 0.5 W / (m 2·K), the ambient temperature of the pipeline is 26°C, the initial pressure of the fluid in the pipeline is 9.2 MPa, and the initial temperature is 41°C.
[0027] The pipeline boundary conditions include a simulation time of 130 s. The starting point of the pipeline is a velocity boundary with a fixed velocity of 0. The ending point of the pipeline is a mass flow boundary. The flow velocity of the fluid in the pipeline is calculated using the small-hole leakage formula as shown in Equation (1).
[0028] (1) In the formula, M is the mass flow rate of the fluid in the pipeline, kg / s; C d is a coefficient, which can be taken as 1.0; A xiao is the area of the leakage small hole, which is the cross-sectional area of the pipeline in this embodiment, m 2 ; M w is the relative molecular mass of the fluid in the pipeline, kg / mol; γ is the adiabatic index; R is the heat capacity of the medium, 8.314 J / (mol·K); T is the temperature of the medium, K; P 0 is the back pressure, Pa; P is the pressure, Pa.
[0029] Among them, the flow velocity of the fluid in the pipeline is equal to the mass flow rate of the fluid in the pipeline divided by the medium density and the cross-sectional area of the pipeline.
[0030] According to the determined pipeline medium, pipeline parameters, and pipeline boundary conditions, using the phase equilibrium model and the thermophysical property parameter model, the physical property parameters of each cross-section of the pipeline at each time layer are simulated to obtain the physical property parameters of the homogeneous phase of each cross-section of the pipeline at each time layer.
[0031] Among them, the phase equilibrium model and the thermophysical property parameter model are constructed based on the GERG-2008 equation of state.
[0032] In this embodiment, when performing transient simulation on the fluid in the pipeline to determine the physical property parameters of the homogeneous phase of each cross-section in the pipeline, the initial state is limited to the state at time 0. The result of one solution using the characteristic line method is the result after experiencing one time step. The current time layer is 0 + △t. Then, the wave velocity at the current time layer is calculated to determine the next time step. Then, the characteristic line method performs another solution, and the current time layer is 0 + △t + △t, and so on until the time step is greater than the set simulation time, and the simulation ends.
[0033] The time step of each time layer is determined according to the maximum value of the wave velocities of all cross-sections in the previous time layer. By dynamically updating the time step of each time layer, the calculation can be ensured to be stable and the divergence risk can be avoided. The process of determining the time step of the current time layer includes: Obtain the maximum value of the wave velocities of all cross-sections in the previous time layer; Determine the time step of the current time layer according to the maximum value of the wave velocities of all cross-sections in the previous time layer. It is calculated according to formula (2): (2) In the formula, is the time step of the current time layer, s; CFL The range is 0 - 1, and generally 0.5 is taken considering the calculation accuracy and calculation efficiency; is the space step, m, and the space step is equal to the pipeline length divided by the number of pipeline segments; a max is the maximum value of the wave velocities of all cross-sections of the pipeline in the previous time layer.
[0034] Among them, the time step of the first time layer is determined according to the given initial conditions. The given initial conditions include the pressure, temperature and flow velocity inside the pipe. Using the pressure, temperature, phase equilibrium model and thermophysical property model, the wave velocity of each cross-section inside the pipe can be calculated. Based on the maximum value of the wave velocity, the time step can be calculated using formula (2), and this time step is used as the time step of the first time layer.
[0035] In the embodiment of the present application, taking the calculation of the physical property parameters of the homogeneous phase of each cross-section of the pipeline in the current time layer as an example, the process of the physical property parameters of the homogeneous phase of each cross-section of the pipeline is described.
[0036] The process of determining the physical property parameters of the homogeneous phase of each cross-section of the pipeline in the current time layer includes: First, perform hydraulic calculation. According to the hydraulic characteristic equation, calculate and determine the flow velocity v and the head H of each cross-section of the pipeline in the current time layer. Among them, the hydraulic characteristic equations are as shown in formula (3) and formula (4); After that, perform thermal calculation. According to the thermal characteristic equation, calculate and determine the temperature T of each cross-section of the pipeline in the current time layer. Among them, the thermal characteristic equation is as shown in formula (5).
[0037] (3) (4) (5) In the formula, v is the flow velocity, m / s; g is the acceleration of gravity, 9.8m / s 2 ; H is the head, m;λ is the friction coefficient; D is the outer diameter of the pipe, m; d is the inner diameter of the pipe, m; a is the water hammer wave velocity, m / s; c p is the specific heat capacity at constant pressure of the medium inside the pipe, J / (kg·K); β is the volume expansion coefficient of the medium inside the pipe, 1 / K; ρ is the density of the medium inside the pipe, kg / m 3 ; K is the overall heat transfer coefficient of the heat exchange between the medium inside the pipe and the external environment, W / (m 2 ·K); T is the temperature of the pipe cross-section, which is the temperature of the liquid inside the pipe, K; T 0 is the environmental temperature, K.
[0038] According to the head H of each cross-section of the pipe at the current time level, calculate and determine the pressure of each cross-section of the pipe at the current time level; according to the temperature T and pressure of each cross-section of the pipe, perform a phase equilibrium calculation on each cross-section of the pipe to determine the gas phase fraction of each cross-section of the pipe at the current time level.
[0039] Preferably, use the constructed phase equilibrium model to perform a phase equilibrium calculation on each cross-section of the pipe to determine the gas phase fraction of each cross-section.
[0040] According to the gas phase fraction of each cross-section, judge the phase state of each cross-section. Specifically: When the gas phase fraction is 0, the phase state of the cross-section is pure liquid phase; When the gas phase fraction is greater than 0 and less than 1, the phase state of the cross-section is gas-liquid two-phase.
[0041] For the cross-section with the phase state of pure liquid phase, calculate and determine the liquid phase physical property parameters of this cross-section according to the temperature of this cross-section. The liquid phase physical property parameters are the physical property parameters of the homogeneous phase of this cross-section; For the cross-section with the phase state of gas-liquid two-phase, calculate and determine the top temperature of the cross-section according to the cross-section temperature and the top temperature calculation model, calculate the gas phase physical property parameters according to the top temperature of this cross-section, calculate the liquid phase physical property parameters according to the bottom temperature of this cross-section, and perform weighted fusion on the gas phase physical property parameters and the liquid phase physical property parameters to obtain the physical property parameters of the homogeneous phase of this cross-section.
[0042] Since the present application is directed to a cryogenic liquid pipeline, there is no pure gas phase cross-section in the pipeline.
[0043] Among them, both the liquid phase physical property parameters and the gas phase physical property parameters are calculated according to the constructed thermal physical property parameter model.
[0044] The top temperature calculation model includes Equation (6), Equation (7) and Equation (8), specifically:
[0045] (6) (7) (8) In the formula, the subscript i represents the i time layer; the subscript j represents the j th cross-section of the pipeline; represents the temperature at the top of the cross-section of the pipeline, K; T represents the temperature of the cross-section of the pipeline, which is the temperature of the cross-section of the pipeline calculated by formula (5), K; t is the cumulative time at the current time layer, s; k The empirical coefficient is taken as 4.0 here; L represents the latent heat of vaporization, kJ / kg; C p represents the specific heat capacity, kJ / (kg·K); The increment of the gas-phase fraction, kg / kg; represents the gas-phase fraction, kg / kg.
[0046] For the cross-section with the gas-liquid two-phase state, using the gas-phase fraction of this cross-section, the gas-phase physical property parameters and liquid-phase physical property parameters of this cross-section are weighted and fused to obtain the physical property parameters of the homogeneous phase of this cross-section, which can be calculated by formula (9).
[0047] (9) In the formula, value mix is the physical property parameter of the homogeneous phase after mixing the gas phase and the liquid phase; value g is the gas-phase physical property parameter; value l is the liquid-phase physical property parameter; is the gas-phase fraction.
[0048] Among them, the physical property parameters include density, viscosity, specific heat capacity, volume expansion coefficient, wave velocity, etc.
[0049] After that, determine the wave velocity of the homogeneous phase of each cross-section at the current time layer. Specifically: for the cross-section with the gas-liquid two-phase state, according to the liquid-phase wave velocity and gas-phase wave velocity of this cross-section, determine the wave velocity of the homogeneous phase of this cross-section, that is, the wave velocity of this cross-section; among them, the wave velocity of the homogeneous phase is the square root of the sum of the squares of the liquid-phase wave velocity and the gas-phase wave velocity, as shown in formula (10).
[0050] (10) In the formula, a represents the wave velocity of the homogeneous phase, m / s;a l represents the liquid-phase wave velocity, m / s; a g represents the gas-phase wave velocity, m / s.
[0051] For the cross-section with the physical phase state of pure liquid phase, the wave velocity in the calculated physical properties parameters is the final cross-section wave velocity.
[0052] Determine the time step of the next time layer based on the wave velocities of each cross-section of the pipeline at the current time layer calculated.
[0053] Based on the determined time step of the current time layer, determine the time of the current time layer, where the time of the current time layer is equal to the time of the previous layer plus the time step. Judge whether the time of the current time layer reaches the simulation time. If it does not reach the simulation time, determine the time step of the next time layer based on the wave velocities of each cross-section of the pipeline at the current time layer calculated, and calculate and determine the physical properties parameters and cross-section wave velocities of the homogeneous phase of each cross-section of the pipeline at the next time layer; if it reaches the simulation time, stop the transient calculation.
[0054] From Figure 2 It can be seen that as the leakage time increases, the pressure at the starting point of the pipeline drops rapidly first. Around 2 s, CO2 starts to vaporize, and the pressure drops slowly. Finally, at 85 s, the pressure drops to the triple point of CO2, and the simulation ends. It can be seen that the simulated value of the pressure in the whole process is very close to the experimental value.
[0055] From Figure 3 It can be seen that as the leakage time increases, the liquid temperature at the bottom of the starting point of the pipeline has been in a downward state, and the gas-phase temperature at the top of the starting point of the pipeline drops first and then basically remains unchanged. This is because at the beginning of vaporization, the vaporization amount is small, and there is more low-temperature liquid at the top of the pipeline, so the temperature at the top is more affected by the low-temperature liquid. As the gas-phase content increases, the liquid absorbs heat and becomes a gas phase with a higher temperature and accumulates at the top, and the temperature at the top of the pipeline basically remains unchanged.
[0056] From Figure 4 and Figure 5 it can be seen that as the leakage time increases, the gas-phase fraction increases, the gas-liquid interface moves downward, the liquid temperature has been dropping, the gas-phase temperature is higher than the liquid temperature, drops first and then basically remains unchanged. Among them, Figure 5 in (a) is the temperature of the cross-section at the starting point of the pipeline at 11.00 s, Figure 5 in (b) is the temperature of the cross-section at the starting point of the pipeline at 24.08 s, Figure 5 in (c) is the temperature of the cross-section at the starting point of the pipeline at 51.18 s, Figure 5 in (d) is the temperature of the cross-section at the starting point of the pipeline at 80.00 s, Figure 5 in (e) is the temperature of the cross-section at the starting point of the pipeline at 93.97 s, Figure 5The temperature at the starting cross-section of the pipeline at 128.17 s is (f).
[0057] A transient simulation of a cryogenic liquid pipeline considering phase change provided by the present invention solves phase equilibrium and thermophysical property parameters based on the GERG-2008 equation of state, and is coupled with a homogeneous flow model including equations (3), (4) and (5), considering the influence of latent heat of vaporization, to establish a transient simulation of a cryogenic liquid pipeline considering phase change. The simulation shows that the transient simulation of a cryogenic liquid pipeline considering phase change provided by the present invention can perform transient simulation of a cryogenic liquid pipeline well, has the characteristics of clear calculation process and simple method, makes up for the deficiency that the existing two-phase flow model cannot simulate gas-liquid temperature stratification, and provides a technical solution for the process design and simulation of cryogenic liquid pipelines.
[0058] Example 2 In this example, a transient simulation system of a cryogenic liquid pipeline considering phase change is disclosed, including:[[]] A data acquisition unit for acquiring pipeline parameters, pipeline medium and pipeline boundary conditions; A hydraulic and thermal parameter calculation unit for determining the pressure and temperature of each cross-section of the pipeline at each time layer by using the pipeline parameters, pipeline medium and pipeline boundary conditions; A gas phase fraction calculation unit for performing phase equilibrium calculation on each cross-section of the pipeline according to the temperature and pressure of each cross-section of the pipeline at each time layer to determine the gas phase fraction of each cross-section of the pipeline at each time layer; A phase state judgment unit for judging the phase state of each cross-section according to the gas phase fraction; A physical property parameter calculation unit for determining the top temperature of a cross-section with a gas-liquid two-phase state, calculating gas phase physical property parameters according to the top temperature of the cross-section, calculating liquid phase physical property parameters according to the temperature of the cross-section, and performing weighted fusion on the gas phase physical property parameters and the liquid phase physical property parameters to obtain the physical property parameters of the homogeneous phase of the cross-section.
[0059] The present invention also discloses a computer device, which includes:[[]] A processor suitable for executing a computer program; A computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by the processor, it realizes a transient simulation method of a cryogenic liquid pipeline considering phase change disclosed in Example 1.
[0060] The present invention also discloses a computer-readable storage medium, which stores a computer program, and the computer program is suitable for being loaded and executed by a processor to implement a transient simulation method of a cryogenic liquid pipeline considering phase change disclosed in Example 1.
[0061] The present invention also discloses a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements a transient simulation method for a cryogenic liquid pipeline considering phase change disclosed in Embodiment 1.
[0062] The method disclosed in Embodiment 1 can be directly embodied as being executed by a hardware processor, or by a combination of hardware and software modules in the processor. The software module can be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.
[0063] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with this embodiment can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.
[0064] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.
Claims
1. A transient simulation method for cryogenic liquid pipelines considering phase change, characterized in that, including: Obtain pipeline parameters, pipeline medium, and pipeline boundary conditions; Utilize the pipeline parameters, pipeline medium, and pipeline boundary conditions to determine the pressure and temperature of each cross-section of the pipeline at each time layer; According to the temperature and pressure of each cross-section of the pipeline at each time layer, perform phase equilibrium calculations on each cross-section of the pipeline to determine the gas phase fraction of each cross-section of the pipeline at each time layer; Judge the phase state of each cross-section according to the gas phase fraction; For the cross-sections with a gas-liquid two-phase state, determine the top temperature of the cross-section, calculate the gas phase physical properties parameters according to the top temperature of the cross-section, calculate the liquid phase physical properties parameters according to the temperature of the cross-section, and perform weighted fusion on the gas phase physical properties parameters and the liquid phase physical properties parameters to obtain the physical properties parameters of the homogeneous phase of the cross-section.
2. The transient simulation method for a cryogenic liquid pipeline considering phase change according to claim 1, wherein For the cross-sections with a pure liquid phase state, calculate and determine the liquid phase physical properties parameters of the cross-section according to the temperature of the cross-section, and the liquid phase physical properties parameters are the physical properties parameters of the homogeneous phase of the cross-section.
3. The transient simulation method for cryogenic liquid pipelines considering phase change as claimed in claim 1, wherein Obtain the maximum value of the wave speeds of all cross-sections in the previous time layer; Determine the time step of the current time layer according to the maximum value of the wave speeds of all cross-sections in the previous time layer.
4. A transient simulation method for a cryogenic liquid pipeline considering phase change according to claim 1, characterized in that, For the cross-sections with a gas-liquid two-phase state, determine the wave speed of the homogeneous phase of the cross-section, that is, the wave speed of the cross-section, according to the liquid phase wave speed and the gas phase wave speed of the cross-section; wherein, the wave speed of the homogeneous phase is the square root of the sum of the squares of the liquid phase wave speed and the gas phase wave speed.
5. A transient simulation method for cryogenic liquid pipelines considering phase change as claimed in claim 1, characterized in that, Calculate and determine the top temperature of the cross-section according to the cross-section temperature and the top temperature calculation model.
6. A transient simulation method for a cryogenic liquid pipeline considering phase change according to claim 1, characterized in that When the gas phase fraction is 0, the phase state of the cross-section is a pure liquid phase; When the gas phase fraction is greater than 0 and less than 1, the phase state of the cross-section is a gas-liquid two-phase state.
7. A transient simulation system for cryogenic liquid pipelines considering phase change, characterized in that, including: A data acquisition unit for obtaining pipeline parameters, pipeline medium, and pipeline boundary conditions; A hydraulic and thermal parameter calculation unit for utilizing the pipeline parameters, pipeline medium, and pipeline boundary conditions to determine the pressure and temperature of each cross-section of the pipeline at each time layer; A gas phase fraction calculation unit for performing phase equilibrium calculations on each cross-section of the pipeline according to the temperature and pressure of each cross-section of the pipeline at each time layer to determine the gas phase fraction of each cross-section of the pipeline at each time layer; A phase state judgment unit for judging the phase state of each cross-section according to the gas phase fraction; A physical properties parameter calculation unit for, for the cross-sections with a gas-liquid two-phase state, determining the top temperature of the cross-section, calculating the gas phase physical properties parameters according to the top temperature of the cross-section, calculating the liquid phase physical properties parameters according to the temperature of the cross-section, and performing weighted fusion on the gas phase physical properties parameters and the liquid phase physical properties parameters to obtain the physical properties parameters of the homogeneous phase of the cross-section.
8. An electronic device, characterized in that, The device includes: A processor suitable for executing a computer program; A computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by the processor, it implements a transient simulation method for a cryogenic liquid pipeline considering phase change according to any one of claims 1-6.
9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded and executed by the processor to implement a transient simulation method for a cryogenic liquid pipeline considering phase change according to any one of claims 1-6.
10. A computer program product, characterized in that, The computer program product includes a computer program, and when the computer program is executed by the processor, it implements a transient simulation method for a cryogenic liquid pipeline considering phase change according to any one of claims 1-6.