Method, system and device for determining one-dimensional heat transfer parameters at the wall of buried pipeline

Abstract

The method, system and device for determining one-dimensional heat transfer parameters at the wall of a buried pipeline disclosed in the present invention belong to the technical field of one-dimensional heat transfer parameter calculation at the wall of the buried pipeline, and include: obtaining parameter data related to the one-dimensional heat transfer parameter calculation at the wall of the buried pipeline; constructing multiple non-steady-state heat transfer models containing only a single unit temperature boundary condition according to the parameter data; numerically solving each non-steady-state heat transfer model containing only a single unit temperature boundary condition to obtain the mathematical relationship between the one-dimensional heat transfer parameter at the wall of the buried pipeline under each single unit temperature boundary condition and time; performing a segmented convolution calculation and adding the mathematical relationship between the one-dimensional heat transfer parameter at the wall of the buried pipeline under each single unit temperature boundary condition and the temperature boundary condition at the corresponding boundary in the obtained parameter data, to obtain the one-dimensional heat transfer parameter at the wall of the buried pipeline under the joint influence of all non-homogeneous boundary conditions. The method realizes the rapid calculation of the one-dimensional heat transfer parameter at the wall of the buried pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of one-dimensional heat transfer parameter calculation, and in particular to a method, system and device for determining one-dimensional heat transfer parameters at a buried pipeline wall. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Long-distance pipelines are laid underground, and the outside of the pipeline is a semi-infinite soil heat conduction space. Changes in the temperature of the medium transported in the pipeline and changes in the atmospheric environment temperature will cause the soil temperature field outside the pipeline to be in a non-steady state; the non-steady temperature distribution of the soil outside the pipeline causes the temperature gradient near the pipe wall to be non-steady, that is, the heat exchange between the pipeline and the surrounding environment is always dynamically changing, and further affects the flow and mass transfer process of the medium in the pipeline. For example: (1) During the preheating process of hot oil pipeline commissioning, the non-steady heat exchange inside and outside the pipeline affects the calculation of the preheating time for commissioning. (2) During the shutdown and restart process of hot waxy crude oil pipeline, the non-steady heat exchange inside and outside the pipeline affects the calculation of the safe shutdown time of the pipeline. (3) During the alternating transportation process of hot and cold oil products, the non-steady heat exchange inside and outside the pipeline affects the calculation of the dynamic thermal and hydraulic characteristics of the oil products in the pipeline. (4) During the sequential transportation process of finished oil pipelines, the non-steady heat exchange inside and outside the pipeline affects the calculation of the mixed oil interface position and mixed oil length. In addition to oil pipelines, urban heating pipelines, geothermal pipelines and various types of hot and cold alternating pipelines also have non-steady-state temperature fields in the semi-infinite heat conduction space outside the pipes, which affects the thermal and hydraulic characteristics of the medium in the pipes and the calculation of related parameters.

[0004] For long-distance pipelines, the pipeline is usually regarded as a one-dimensional structure, and the unsteady heat exchange process between the pipeline wall and the surrounding environment needs to be characterized by one-dimensional heat transfer parameters. Currently, for the unsteady heat exchange process inside and outside the pipe, the two-dimensional unsteady temperature field of each microelement pipe section under dynamic boundary conditions is often calculated by numerical calculation methods, so as to obtain one-dimensional heat transfer parameters such as heat flux density and equivalent total heat transfer coefficient at the pipeline wall, which are then used for heat exchange calculation inside and outside the pipe. This calculation method requires a large number of grid node iterative calculations, which takes a long time to calculate and is difficult to meet the real-time calculation of long-distance pipeline dynamic processes. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a method, system and equipment for determining one-dimensional heat transfer parameters at the wall of a buried pipeline, thereby realizing rapid calculation of one-dimensional heat transfer parameters at the wall of a buried pipeline.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] First, a method for determining the one-dimensional heat transfer parameters at the wall of a buried pipeline is proposed, including:

[0008] Obtain various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline;

[0009] According to the parameter data, multiple unsteady heat transfer models with only a single unit temperature boundary condition are constructed;

[0010] Numerical solution is performed for each unsteady heat transfer model with only a single unit temperature boundary condition to obtain the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition;

[0011] The mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall under each single temperature boundary condition;

[0012] The one-dimensional heat transfer parameters at the pipe wall under all single temperature boundary conditions are added together to obtain the one-dimensional heat transfer parameters at the pipe wall of the buried pipeline under the influence of all non-homogeneous boundary conditions.

[0013] Furthermore, various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline include the outer diameter of the pipeline, the buried depth of the pipeline, the thermal influence zone range of the heat conduction space outside the pipeline, the physical properties of the solid material, the initial temperature field distribution, and the temperature boundary conditions at each boundary position.

[0014] Furthermore, the temperature boundary condition in the unsteady-state heat transfer model containing only a single unit temperature boundary condition is a first-type temperature boundary condition, a second-type temperature boundary condition, or a third-type temperature boundary condition.

[0015] Furthermore, the one-dimensional heat transfer parameter at the tube wall is the heat flux density at the tube wall or the dynamic total heat transfer coefficient at the tube wall.

[0016] Furthermore, the process of the segmented convolution calculation is as follows: for the one-dimensional heat transfer parameter in the non-steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the non-steady-state section;

[0017] For the one-dimensional heat transfer parameter in the steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter that has not reached a stable value and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter that has reached a stable value is multiplied by the temperature condition value of the time node corresponding to the steady-state moment in the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is added to the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section to obtain the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the steady-state section.

[0018] Furthermore, according to the gradient change of the one-dimensional heat transfer parameter with respect to time in the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under the single unit temperature boundary condition, it is determined whether the one-dimensional heat transfer parameter is in the steady state section or the unsteady state section.

[0019] Furthermore, the gradient change of the one-dimensional heat transfer parameter with respect to time in the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under the boundary condition of a single unit temperature is calculated;

[0020] When the gradient change of the one-dimensional heat transfer parameter with respect to time is less than or equal to the set error value, it is determined that the one-dimensional heat transfer parameter is in the steady state section;

[0021] When the gradient change of the one-dimensional heat transfer parameter with respect to time is greater than the set error value, it is determined that the one-dimensional heat transfer parameter is in a non-steady-state section.

[0022] Secondly, a system for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline is proposed, including:

[0023] A data acquisition unit, used to acquire various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline;

[0024] A model building unit, used for building a plurality of unsteady-state heat transfer models containing only a single unit temperature boundary condition according to various parameter data;

[0025] The one-dimensional heat transfer parameter determination unit is used to numerically solve each non-steady-state heat transfer model containing only a single unit temperature boundary condition, and obtain the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition; the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition is segmentedly convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under each single temperature boundary condition; the one-dimensional heat transfer parameters at the pipe wall under all single temperature boundary conditions are added together to obtain the one-dimensional heat transfer parameters at the buried pipeline wall under the joint influence of all non-homogeneous boundary conditions.

[0026] Furthermore, the one-dimensional heat transfer parameter determination unit is used for the process of segmented convolution calculation: for the one-dimensional heat transfer parameter in the non-steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under the single temperature boundary condition of the non-steady-state section; for the one-dimensional heat transfer parameter in the steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter that has not reached a stable value and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the single temperature boundary condition of the steady-state section. The one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is obtained; the one-dimensional heat transfer parameter that has reached a stable value is multiplied by the temperature condition value of the time node corresponding to the steady-state moment in the temperature boundary condition at the corresponding boundary in the acquired parameter data, and the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section is obtained; the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is added to the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section, and the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the steady-state section is obtained.

[0027] In a third aspect, a computer device is provided, the device comprising:

[0028] a processor adapted to execute a computer program;

[0029] A computer-readable storage medium having a computer program stored therein, wherein when the computer program is executed by the processor, the method for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline proposed in the first aspect is implemented.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention proposes a method, system and device for determining one-dimensional heat transfer parameters at the wall of a buried pipeline. The method constructs multiple non-steady-state heat transfer models containing only a single unit temperature boundary condition, and then solves each non-steady-state heat transfer model containing only a single unit temperature boundary condition to obtain a mathematical relationship between the one-dimensional heat transfer parameter at the wall under each single unit temperature boundary condition and time; after performing a segmented convolution calculation on the mathematical relationship between the one-dimensional heat transfer parameter at the wall under each single unit temperature boundary condition and the temperature boundary condition at the corresponding boundary in the acquired parameter data, the one-dimensional heat transfer parameters at the wall under each single temperature boundary condition obtained by the convolution calculation are added to obtain the one-dimensional heat transfer parameters at the wall of the buried pipeline; without performing iterative calculation of a large number of grid nodes, the rapid calculation of the one-dimensional heat transfer parameters at the wall of the buried pipeline is improved.

[0032] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0034] Figure 1 It is a flow chart of a method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline disclosed in an embodiment;

[0035] Figure 2 It is a schematic diagram of a geometric model of a two-dimensional non-steady-state temperature field in a pipe cross section disclosed in an embodiment;

[0036] Figure 3 The mapping relationship between heat flux and time disclosed in the embodiment Schematic diagram;

[0037] Figure 4 The mapping relationship between heat flux and time disclosed in the embodiment Schematic diagram;

[0038] Figure 5 It is a schematic diagram of the comparison and verification results of the actual value and calculated value of the heat flux density disclosed in the embodiment. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0041] 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 form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0043] Example 1

[0044] At present, for the non-steady-state heat exchange process inside and outside the pipe, the two-dimensional non-steady-state temperature field of each micro-element pipe section under dynamic boundary conditions is often calculated by numerical calculation methods, so as to obtain one-dimensional heat transfer parameters such as heat flux density at the pipe wall and equivalent total heat transfer coefficient, which are then used for heat exchange calculation inside and outside the pipe. This calculation method requires a large number of grid node iterative calculations, which takes a long time to calculate and is difficult to meet the real-time calculation of long-distance pipeline dynamic processes.

[0045] To this end, this embodiment proposes a method for determining the one-dimensional heat transfer parameters at the wall of a buried pipeline. The method realizes efficient and accurate calculation of the one-dimensional heat transfer parameters at the wall of a buried pipeline taking into account the influence of the non-steady-state temperature field outside the pipeline, and realizes the dynamic characterization of the non-steady-state heat exchange process between the oil product in the long-distance buried pipeline and the semi-infinite soil heat conduction space outside the pipeline.

[0046] The method for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline proposed in this embodiment is as follows: Figure 1-Figure 5 As shown, including:

[0047] S1: Obtain various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline.

[0048] Among them, the parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline include the outer diameter of the pipeline, the buried depth of the pipeline, the thermal influence zone range of the heat conduction space outside the pipeline, the physical properties of the solid material, the initial temperature field distribution, and the temperature boundary conditions at each boundary position.

[0049] The physical properties of the solid material in the heat conduction space outside the pipeline include the density of the solid material Specific heat capacity of solid materials and the thermal conductivity of solid materials .

[0050] S2: Based on the parameter data, construct multiple unsteady-state heat transfer models containing only a single unit temperature boundary condition.

[0051] Among them, the temperature boundary condition in the unsteady-state heat transfer model containing only a single unit temperature boundary condition is any one of the first type of temperature boundary condition, the second type of temperature boundary condition and the third type of temperature boundary condition.

[0052] The unsteady heat transfer model with only a single unit temperature boundary condition is: In the formula, is the density of the solid material in the heat conduction space, is the specific heat capacity of the solid material in the heat-conducting space, is the thermal conductivity of the solid material in the heat-conducting space; For the border The temperature field is a non-steady-state field with a unit temperature boundary condition at the non-homogeneous boundary and homogeneous boundary conditions at the other boundaries. i =1, 2, …, n ; n Indicates the number of boundaries with non-homogeneous boundary conditions in the unsteady heat transfer model; Perpendicular to the boundary The external normal direction derivative of ; , For the border j The corresponding boundary condition coefficient is a constant, j =1, 2, …, s; s represents the number of boundaries in the unsteady heat transfer model, ;when When j With the first kind of boundary conditions, when When j With the second type of boundary conditions, when and When j It has the third type of boundary conditions; is the Kronecker symbol, when i=j hour, , when i≠j hour, .

[0053] S3: Numerically solve each unsteady-state heat transfer model that only contains a single unit temperature boundary condition to obtain the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition.

[0054] In this embodiment, each unsteady-state heat transfer model containing only a single unit temperature boundary condition is solved by a numerical calculation method to obtain a numerical solution of a one-dimensional heat transfer parameter at the pipe wall in each unsteady-state heat transfer model containing only a single unit temperature boundary condition, that is, a one-dimensional heat transfer parameter value at the pipe wall corresponding to each discrete moment containing only a single unit temperature boundary condition, and based on the one-dimensional heat transfer parameter value at the pipe wall corresponding to each discrete moment containing the single unit temperature boundary condition, a mathematical relationship between the one-dimensional heat transfer parameter at the pipe wall and time under each single unit temperature boundary condition is obtained. .

[0055] S4: Perform a segmented convolution calculation on the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition and the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under each single temperature boundary condition; add up the one-dimensional heat transfer parameters at the pipe wall under all single temperature boundary conditions to obtain the one-dimensional heat transfer parameter at the buried pipeline wall under the influence of all non-homogeneous boundary conditions.

[0056] This embodiment uses the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition as follows: The temperature boundary conditions at the corresponding boundary in the parameter data obtained by S1 Perform segmented convolution calculation to obtain the one-dimensional heat transfer parameters at the tube wall under each single temperature boundary condition. ; The unsteady heat transfer model corresponding to a single temperature boundary condition is: .in, For the border The temperature boundary condition is non-homogeneous at the point, and the other boundaries are all non-steady-state temperature fields under homogeneous boundary conditions; For the border The corresponding non-homogeneous boundary condition is i=j hour, , when i≠j hour, .

[0057] The one-dimensional heat transfer parameters at the tube wall under all single temperature boundary conditions are Add the sum to obtain the one-dimensional heat transfer parameters at the buried pipeline wall under the influence of all non-homogeneous boundary conditions. ; The unsteady heat transfer model corresponding to the combined influence of all temperature boundary conditions is: ,in, is the unsteady temperature field under the influence of all nonhomogeneous boundary conditions.

[0058] The one-dimensional heat transfer parameters disclosed in this embodiment include a steady-state section and a non-steady-state section; according to the mathematical relationship between the one-dimensional heat transfer parameters and time at the pipe wall under a single unit temperature boundary condition The gradient change of the one-dimensional heat transfer parameter with respect to time determines whether the one-dimensional heat transfer parameter is in the steady-state section or the unsteady-state section.

[0059] The process of judging whether the one-dimensional heat transfer parameters are in the steady state or the unsteady state is as follows:

[0060] Calculate the mathematical relationship between one-dimensional heat transfer parameters and time at the pipe wall under single unit temperature boundary conditions The gradient variation of one-dimensional heat transfer parameters with respect to time;

[0061] When the gradient change of the one-dimensional heat transfer parameter with respect to time is less than or equal to the set error value, it is determined that the one-dimensional heat transfer parameter is in the steady state section;

[0062] When the gradient change of the one-dimensional heat transfer parameter with respect to time is greater than the set error value, it is determined that the one-dimensional heat transfer parameter is in a non-steady-state section.

[0063] In this embodiment, the process of performing segmented convolution calculation on the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition and the temperature boundary condition at the corresponding boundary in the acquired parameter data is as follows: for the one-dimensional heat transfer parameter in the non-steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter and time is convolved with the temperature boundary condition at the corresponding boundary in the parameter data acquired in S1 to obtain the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the non-steady-state section, that is: , where is the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition corresponding to time t; is the temperature boundary condition at the corresponding boundary in the obtained parameter data; For time t The corresponding one-dimensional heat transfer parameters at the tube wall under the boundary condition of single unit temperature; is the stabilization time, when When , it is in the steady state.

[0064] For the one-dimensional heat transfer parameter in the steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter that has not reached a stable value and time is convoluted with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter that has reached a stable value is multiplied by the temperature condition value of the time node corresponding to the steady-state moment in the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is added to the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section to obtain the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the steady-state section. ; In the formula, is the stable value of one-dimensional heat transfer parameter; It is the temperature condition value at the time corresponding to the steady-state moment in the parameter data obtained by S1.

[0065] The one-dimensional heat transfer parameters at the tube wall under all single temperature boundary conditions are The one-dimensional heat transfer parameters at the buried pipeline wall under the influence of all non-homogeneous boundary conditions are obtained by summing up the calculations. , .

[0066] The one-dimensional heat transfer parameters at the pipe wall involved in this embodiment include the heat flux density at the pipe wall and the total heat transfer coefficient at the pipe wall. That is, the method disclosed in this embodiment can be used to calculate and determine the heat flux density at the pipe wall, and can also be used to calculate and determine the total heat transfer coefficient at the pipe wall. For temperature boundary conditions that change arbitrarily with time and space, it is only necessary to obtain the mathematical relationship between the one-dimensional heat transfer parameters at the pipe wall and time under each single unit temperature boundary condition, and then perform segmented convolution calculation and summation calculation with the temperature boundary condition in turn, so as to obtain the one-dimensional heat transfer parameters at the pipe wall of the buried pipeline in the non-steady-state temperature field under the joint influence of any boundary conditions.

[0067] The method for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline provided in this embodiment is verified by calculating the dynamic heat flux density under actual working conditions.

[0068] Design a case study on the dynamic heat flux density at the wall of an underground oil pipeline corresponding to the actual working condition. The actual working condition is: a single buried hot oil pipeline with a buried depth of =1.5m, the outer diameter of the pipe is 1.0m. The thermal influence zone of the soil outside the pipe is 10m, and the thermal conductivity =1.65W / (m·ºC), density ρ=1700kg / m 3 , specific heat capacity =1300J / (ºC·kg).

[0069] Under actual working conditions, the pipe wall boundary temperature is affected by the oil temperature, the surface boundary temperature is affected by the atmospheric temperature, and the left, right, and lower boundaries are thermally affected areas. The pipe wall boundary and the surface boundary change over time and are non-homogeneous boundaries; the left, right, and lower boundaries are adiabatic boundaries and are non-homogeneous boundaries; then s=5, n=2.

[0070] Set the non-homogeneous time-dependent wall temperature boundary to , the non-homogeneous time-dependent surface temperature boundary is ; At the initial moment, the temperature field is zero. Based on the pipeline burial depth, pipeline outer diameter, and thermal influence zone range, a two-dimensional non-steady-state temperature field geometric model of the pipeline cross section under actual working conditions is established, such as Figure 2 shown.

[0071] In this actual working condition, the unsteady heat transfer model A under the combined influence of all non-homogeneous temperature boundary conditions is: .

[0072] There are two non-homogeneous boundary conditions in the above-mentioned non-steady-state heat transfer model. The corresponding non-steady-state heat transfer models with only a single unit temperature boundary condition include: a non-steady-state heat transfer model with a unit temperature boundary condition on the pipe wall boundary and homogeneous boundary conditions on the other boundaries, and a non-steady-state heat transfer model with a unit temperature boundary condition on the surface boundary and homogeneous boundary conditions on the other boundaries.

[0073] Unsteady heat transfer model with unit temperature boundary condition on the tube wall and homogeneous boundary conditions on the other boundaries for: .

[0074] Unsteady-state heat transfer model with unit temperature boundary conditions on the surface and homogeneous boundary conditions on the other boundaries for: .

[0075] The above two unsteady-state heat transfer models with only a single unit temperature boundary condition are numerically calculated to obtain the numerical solution of the heat flux density at the pipe wall in each model, that is, the heat flux density value at the pipe wall corresponding to each discrete moment with only a single unit temperature boundary condition, thereby obtaining the mathematical relationship between the heat flux density at the pipe wall and time under each single unit temperature boundary condition. .

[0076] Table 1 shows the unsteady heat transfer model in which the pipe wall boundary has a unit temperature boundary condition and the other boundaries are homogeneous boundary conditions. The numerical solution of the heat flux density at the tube wall is: Figure 3 Shown is an unsteady heat transfer model Mathematical relationship between heat flux density at the tube wall and time Table 2 shows the unsteady heat transfer model with unit temperature boundary condition at the surface boundary and homogeneous boundary conditions at other boundaries. The numerical solution of the heat flux density at the tube wall is: Figure 4 Shown is an unsteady heat transfer model Mathematical relationship between heat flux density at the tube wall and time .

[0077] Table 1 Unsteady heat transfer model Numerical solution of heat flux density at the tube wall

[0078]

[0079] Table 2 Unsteady heat transfer model Numerical solution of heat flux density at the middle tube wall

[0080]

[0081] In the mathematical relationship between the heat flux density at the pipe wall and time under the single unit temperature boundary condition, the heat flux density value tends to be stable as the time step increases, and the time gradient approaches zero. In this implementation case, the heat flux density value at the pipe wall corresponding to 51840 time steps is obtained by pre-calculation, and the actual time corresponding to 51840 time steps is 360 days. , Temperature boundary conditions set with corresponding boundaries , Perform segmented convolution calculations to obtain the pipe wall boundary as the temperature boundary condition , the remaining boundaries are all homogeneous boundary conditions for unsteady heat transfer models Heat flux density at the tube wall , the surface boundary is the temperature boundary condition , the remaining boundaries are all homogeneous boundary conditions for unsteady heat transfer models Heat flux density at the tube wall .

[0082] The single wall boundary condition is: The heat flux density at the pipe wall in the unsteady section : .

[0083] The single wall boundary condition is The heat flux density at the wall of the steady-state section : .

[0084] The single surface boundary condition is The heat flux density at the pipe wall in the unsteady section : .

[0085] The single surface boundary condition is The heat flux density at the wall of the steady-state section : In the formula, The unsteady heat transfer model is a unit temperature boundary condition for the pipe wall boundary and homogeneous boundary conditions for the other boundaries. The time node at which the heat flux density at the tube wall reaches the stable stage, in this embodiment, according to the unsteady heat transfer model The time gradient of the heat flux density at the tube wall is set to 4320 time steps; This is an unsteady heat transfer model with unit temperature boundary conditions on the surface boundary and homogeneous boundary conditions on the other boundaries. The time node at which the heat flux density at the tube wall reaches the stable stage, in this embodiment, according to the unsteady heat transfer model The time gradient of the heat flux density at the pipe wall is set to 34560 time steps.

[0086] The pipe wall boundary is obtained by segmented convolution calculation as the temperature boundary condition , unsteady heat transfer model with homogeneous boundary conditions on the other boundaries and the surface boundary is the temperature boundary condition , unsteady heat transfer model with homogeneous boundary conditions on the other boundaries After calculating the dynamic heat flux density under the condition, the heat flux densities are added together to obtain the heat flux density at the tube wall in the unsteady heat transfer model A under the influence of all temperature boundary conditions. : The calculation results are as follows: Figure 5 shown.

[0087] The pipe wall boundary is a temperature boundary condition , the remaining boundaries are all homogeneous boundary conditions for unsteady heat transfer models for: .

[0088] The surface boundary is a temperature boundary condition , the remaining boundaries are all homogeneous boundary conditions for unsteady heat transfer models for: .

[0089] The method disclosed in this embodiment is adaptable to any laying method of the pipeline, regardless of whether the pipeline contains an insulation layer outside, whether the pipeline is laid in a single pipe or in parallel with multiple pipes; it can meet the different buried depths of the pipeline, different pipe diameters and different thermal physical parameters of the surrounding environment. It can be achieved by constructing a non-steady-state heat transfer model containing only a single unit temperature boundary condition, and obtaining the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under the single unit temperature boundary condition. The mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under the single unit temperature boundary condition is convolved with the temperature boundary condition in sequence, and then summed up to obtain the one-dimensional heat transfer parameter at the buried pipeline wall under the influence of all non-homogeneous boundary conditions under the influence of arbitrary boundary conditions. Among them, the one-dimensional heat transfer parameter can be the heat flux density at the pipe wall. q or the total heat transfer coefficient at the tube wall K .

[0090] Example 2

[0091] In this embodiment, a system for determining one-dimensional heat transfer parameters at the wall of a buried pipeline is disclosed, comprising:

[0092] A data acquisition unit, used to acquire various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline;

[0093] A model building unit, used for building a plurality of unsteady-state heat transfer models containing only a single unit temperature boundary condition according to various parameter data;

[0094] The one-dimensional heat transfer parameter determination unit is used to numerically solve each non-steady-state heat transfer model containing only a single unit temperature boundary condition, and obtain the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition; the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition is segmentedly convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under each single temperature boundary condition; the one-dimensional heat transfer parameters at the pipe wall under all single temperature boundary conditions are added together to obtain the one-dimensional heat transfer parameters at the buried pipeline wall under the joint influence of all non-homogeneous boundary conditions.

[0095] Furthermore, the one-dimensional heat transfer parameter determination unit is used for the process of segmented convolution calculation: for the one-dimensional heat transfer parameter in the non-steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under the single temperature boundary condition of the non-steady-state section; for the one-dimensional heat transfer parameter in the steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter that has not reached a stable value and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the single temperature boundary condition of the steady-state section. The one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is obtained; the one-dimensional heat transfer parameter that has reached a stable value is multiplied by the temperature condition value of the time node corresponding to the steady-state moment in the temperature boundary condition at the corresponding boundary in the acquired parameter data, and the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section is obtained; the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is added to the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section, and the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the steady-state section is obtained.

[0096] The present invention also discloses a computer device, which includes:

[0097] a processor adapted to execute a computer program;

[0098] A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium. When the computer program is executed by the processor, the method for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline disclosed in Example 1 is implemented.

[0099] The present invention also discloses a computer-readable storage medium storing a computer program, which is suitable for being loaded by a processor and executing the method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline disclosed in Example 1.

[0100] The present invention also discloses a computer program product, which includes a computer program. When the computer program is executed by a processor, the method for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline disclosed in Example 1 is implemented.

[0101] The method disclosed in Example 1 can be directly embodied as a hardware processor, or can be executed by a combination of hardware and software modules in the processor. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.

[0102] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0103] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline, characterized in that: include: Obtain various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline; According to the parameter data, multiple unsteady heat transfer models with only a single unit temperature boundary condition are constructed; Numerical solution is performed for each unsteady heat transfer model with only a single unit temperature boundary condition to obtain the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition; The mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall under each single temperature boundary condition; Among them, segmentation is the mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under the boundary condition of a single unit temperature, and the change process of the one-dimensional heat transfer parameter over time is divided into a non-steady-state section and a steady-state section; The one-dimensional heat transfer parameters at the pipe wall under all single temperature boundary conditions are added together to obtain the one-dimensional heat transfer parameters at the pipe wall of the buried pipeline under the influence of all non-homogeneous boundary conditions.

2. The method for determining the one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 1, characterized in that: The parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline include the outer diameter of the pipeline, the buried depth of the pipeline, the thermal influence zone of the heat conduction space outside the pipeline, the physical properties of the solid material, the initial temperature field distribution, and the temperature boundary conditions at each boundary position.

3. The method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 1, characterized in that: The temperature boundary conditions in an unsteady heat transfer model that contains only a single unit temperature boundary condition are first-type temperature boundary conditions, second-type temperature boundary conditions, or third-type temperature boundary conditions.

4. The method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 1, characterized in that: The one-dimensional heat transfer parameter at the tube wall is the heat flux density at the tube wall or the dynamic total heat transfer coefficient at the tube wall.

5. The method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 1, characterized in that: The process of segmented convolution calculation is as follows: for the one-dimensional heat transfer parameter in the non-steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under the single temperature boundary condition of the non-steady-state section; For the one-dimensional heat transfer parameter in the steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter that has not reached a stable value and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter that has reached a stable value is multiplied by the temperature condition value of the time node corresponding to the steady-state moment in the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is added to the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section to obtain the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the steady-state section.

6. The method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 5, characterized in that: According to the gradient change of the one-dimensional heat transfer parameter with respect to time in the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under the single unit temperature boundary condition, it is determined whether the one-dimensional heat transfer parameter is in the steady state section or the unsteady state section.

7. The method for determining one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 6, characterized in that: Calculate the gradient change of one-dimensional heat transfer parameter with respect to time in the mathematical relationship between one-dimensional heat transfer parameter and time at the tube wall under single unit temperature boundary conditions; When the gradient change of the one-dimensional heat transfer parameter with respect to time is less than or equal to the set error value, it is determined that the one-dimensional heat transfer parameter is in the steady state section; When the gradient change of the one-dimensional heat transfer parameter with respect to time is greater than the set error value, it is determined that the one-dimensional heat transfer parameter is in a non-steady-state section.

8. A system for determining one-dimensional heat transfer parameters at the wall of a buried pipeline, characterized in that: include: A data acquisition unit, used to acquire various parameter data related to the calculation of one-dimensional heat transfer parameters at the wall of the buried pipeline; A model building unit, used for building a plurality of unsteady-state heat transfer models containing only a single unit temperature boundary condition according to various parameter data; The one-dimensional heat transfer parameter determination unit is used to numerically solve each unsteady-state heat transfer model with only a single unit temperature boundary condition, and obtain the mathematical relationship between the one-dimensional heat transfer parameter and time at the pipe wall under each single unit temperature boundary condition; The mathematical relationship between the one-dimensional heat transfer parameter and time at the tube wall under each single unit temperature boundary condition is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall under each single temperature boundary condition; The one-dimensional heat transfer parameters at the pipe wall under all single temperature boundary conditions are added together to obtain the one-dimensional heat transfer parameters at the buried pipeline wall under the influence of all non-homogeneous boundary conditions. Among them, segmentation is the mathematical relationship between the one-dimensional heat transfer parameters at the pipe wall under a single unit temperature boundary condition and time, and the change process of the one-dimensional heat transfer parameters over time is divided into a non-steady-state section and a steady-state section.

9. The system for determining one-dimensional heat transfer parameters at the wall of a buried pipeline according to claim 8, characterized in that: The one-dimensional heat transfer parameter determination unit is used for the process of segmented convolution calculation: for the one-dimensional heat transfer parameter in the non-steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter and time is convoluted with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the pipe wall under the single temperature boundary condition of the non-steady-state section; For the one-dimensional heat transfer parameter in the steady-state section, the mathematical relationship between the one-dimensional heat transfer parameter that has not reached a stable value and time is convolved with the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter that has reached a stable value is multiplied by the temperature condition value of the time node corresponding to the steady-state moment in the temperature boundary condition at the corresponding boundary in the acquired parameter data to obtain the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section; the one-dimensional heat transfer parameter at the tube wall that has not reached a stable value under the single temperature boundary condition of the steady-state section is added to the one-dimensional heat transfer parameter at the tube wall that has reached a stable value under the single temperature boundary condition of the steady-state section to obtain the one-dimensional heat transfer parameter at the tube wall under the single temperature boundary condition of the steady-state section.

10. An electronic device, characterized in that: The device comprises: a processor adapted to execute a computer program; A computer-readable storage medium having a computer program stored therein, wherein when the computer program is executed by the processor, the method for determining the one-dimensional heat transfer parameters at the wall of the buried pipeline according to any one of claims 1 to 7 is implemented.

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