Method for regulating transverse difference of cold conduction performance of permafrost pipeline ventilation embankment

Abstract

The present application relates to the technical field of heat transfer design in ventilation pipeline foundation pipe, in particular to a method for regulating and controlling lateral difference of cold conduction performance of permafrost pipeline ventilation roadbed. The present application divides the ventilation pipeline into segments, respectively calculates the comprehensive heat transfer factor required to achieve the uniformization index at different pipe segment positions according to the current convective heat transfer coefficient distribution of the pipeline, then reasonably selects the enhanced heat transfer wing with specific structure parameters according to the relationship between the comprehensive heat transfer factor and the structure parameters of the enhanced heat transfer wing for arrangement at the fixed point position, so as to compensate for the existing convective heat transfer coefficient at different pipe segment positions, thereby achieving the purpose of regulating and controlling the lateral difference of cold conduction performance of the pipeline ventilation roadbed and improving the uniformity of the embankment environmental temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat transfer design in a ventilation pipe subgrade, and particularly relates to a method for regulating transverse differences in cold conduction performance of a permafrost pipe ventilation subgrade. BACKGROUND

[0002] Compared with a subgrade without a ventilation pipe, a ventilation pipe subgrade has obvious cooling effect, and the temperature influence range of the ventilation pipe can reach 1.0-1.5 meters. The structure of the ventilation pipe subgrade can effectively provide cold energy for embankment soil, and plays an important role in protecting frozen soil and maintaining the stability of frozen embankments.

[0003] At present, one of the main problems of the in-service ventilation pipe subgrade is that the convection heat transfer intensity in the pipe is not uniform, and the overall decreasing law is shown from the air inlet to the air outlet section (such as Figure 1 ), which causes significant differences in the transverse cold conduction performance, and the transverse temperature gradient difference of frozen soil caused by heat conduction of the pipe to the underlying ground is large, and the wide subgrade and the sunshade effect can further exacerbate this phenomenon, resulting in asymmetric temperature field of the ventilation pipe subgrade and the underlying ground, and uneven heat energy in space, which is easy to cause diseases such as subgrade inclination and slope collapse, and affects the safety and healthy operation of the project.

[0004] Therefore, when the ventilation pipe subgrade is designed and applied, the non-uniformity of the embankment environment temperature should be fully considered, and relevant measures should be taken to reduce its influence on the project. SUMMARY

[0005] The present application aims at the problem of large transverse differences in cold conduction performance in the ventilation pipe of the prior art ventilation pipe subgrade, and provides a method for regulating transverse differences in cold conduction performance of a permafrost pipe ventilation subgrade.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A method for regulating transverse differences in cold conduction performance of a permafrost pipe ventilation subgrade, comprising the following steps:

[0008] S1: obtaining the convection heat transfer coefficients of the pipe wall surfaces at different positions in the length direction of the ventilation pipe x 1、 x 2、 x 3、 ……x n h 1、 h 2、 h 3、 ……h n (subscript n is a positive integer, only for distinguishing different positions); determining the uniformization target of the convection heat transfer coefficient as h ​surf ;

[0009] S2: determining the different positions of the ventilation pipe x 1、 x 2、 x 3、 ……x n to achieve the uniformization target of the convective heat transfer coefficient on the surface of the pipe wall h surf the required comprehensive heat transfer factors PEC1, PEC2, PEC3,..., PEC n (PEC stands for performance evaluation criterion);

[0010] S3: determining the structural parameters of the heat transfer enhancement winglet according to the required comprehensive heat transfer factors PEC of the different positions of the ventilation pipe;

[0011] S4: installing the heat transfer enhancement winglet with the corresponding structural parameters on the pipe wall at the different positions x 1、 x 2、 x 3、 ……x n to compensate for the convective heat transfer intensity at the different pipe wall sections of the ventilation pipe.

[0012] The present application achieves the purpose of regulating the lateral difference of the cold guide performance of the ventilation pipe and leveling the convective heat transfer intensity in the pipe by segmenting the ventilation pipe, calculating the required comprehensive heat transfer factors for achieving the uniformization target at different pipe section positions according to the current convective heat transfer coefficient distribution of the pipe, then reasonably selecting the heat transfer enhancement winglet with specific structural parameters according to the relationship between the comprehensive heat transfer factor and the structural parameters of the heat transfer enhancement winglet for arrangement at the specified position, and compensating for the existing convective heat transfer coefficient at different pipe section positions, thereby regulating the lateral difference of the cold guide performance of the ventilation pipe and leveling the convective heat transfer intensity in the pipe. The above-mentioned comprehensive heat transfer factor is used to represent the comprehensive heat transfer performance of the pipe.

[0013] It should be noted that increasing the heat transfer area by setting the heat transfer enhancement winglet in the ventilation heat transfer structure is a common heat transfer enhancement measure, and the specific structure of the heat transfer enhancement winglet can have various structural forms, which is a mature technology, and the heat transfer principle is not described in detail herein.

[0014] As a preferred scheme of the present application, h surf take the maximum value in h 1、 h 2、 h 3、 ……h n , and set h surf the corresponding position is xi , i For 1- n Any of the above, in step S4, during the installation of the enhanced heat exchange fins, x 1. x 2. x 3. ……x n Except x i Install heat exchange fins in locations other than those specified.

[0015] As another possible implementation scheme. h surf The value can also be preset according to actual needs.

[0016] As a preferred embodiment of the present invention, step S1, which involves obtaining the heat transfer coefficient of the pipe wall surface at different locations, includes:

[0017] S11: Model the roadbed for ventilation pipes based on the climate conditions of the area where the roadbed is located in permafrost regions;

[0018] S12: Derives the convective heat transfer coefficient of the pipe wall surface. h Diagram showing the relationship along the length of the ventilation duct;

[0019] S13: On the aforementioned relationship change diagram, discard the points where the convective heat transfer coefficient on both sides of the air inlet and outlet of the ventilation duct is negative, and perform interpolation fitting on the remaining points to obtain... h = P(x) Record the maximum value of the convective heat transfer coefficient near the air inlet on the pipe wall. h max and their corresponding positions x 1;

[0020] S14: with x Using 1 as a baseline, the position of each point is recorded deep into the tube at a preset interval 'a'. x 2. x 3. ……x n And according to the fitting formula h = P(x) Calculate the surface convection heat transfer coefficient for each point. h 2. h 3. ……h n ,in h max > h 2> h 3> h n ;

[0021] Accordingly, in step S4, for x 2. x 3. ……xn Strengthened heat exchange fins with corresponding structural parameters are installed at the pipe wall to compensate for the convective heat transfer intensity, thereby achieving the effect of basically leveling the convective heat transfer intensity at different positions along the axial direction of the ventilation pipe.

[0022] As a preferred embodiment of the present invention, the preset spacing is a, and the value of a is in the range of 0.5m≤a≤2m.

[0023] As a preferred embodiment of the present invention, in step S2... x n The required comprehensive heat transfer factor PEC at the location is obtained by the following expression:

[0024] , n It is a positive integer.

[0025] As a preferred embodiment of the present invention, in step S3, the enhanced heat transfer winglet adopts a rectangular structure, based on the comprehensive heat transfer factor of the enhanced heat transfer winglet. PEC Determine the aspect ratio of the heat transfer winglets l / D and attack angle β .

[0026] This scheme preferably adopts a rectangular reinforced heat transfer winglet, which has a simple structure and convenient structural parameter design. During calculation, the comprehensive heat transfer factor (PEC) and structural parameter (length-to-diameter ratio) of the existing reinforced heat transfer winglet can be used as a reference. l / D and attack angle β The functional relationship between them determines the required performance of the enhanced heat exchange fins to be installed at each location. h surf The corresponding structural parameters required at that time, then by respectively in x 1. x 2. x 3. ……x n Installing enhanced heat transfer fins with appropriate aspect ratios and angles of attack at the pipe wall can compensate for convective heat transfer intensity at different fixed locations, thus improving the efficiency of heat transfer at each location. x 1. x 2. x 3. ……x n The convective heat transfer intensity after installing the enhanced heat exchange fins can all reach [a certain level]. h surf This achieves uniformity of convective heat transfer intensity inside the pipe.

[0027] As another possible implementation method, the heat exchange fins can also adopt other structural forms such as wedges with triangular cross sections. Accordingly, the correspondence between the comprehensive heat transfer factor PEC and the structural parameters should also change accordingly.

[0028] As a preferred scheme of the present application, in step S3, when determining the structural parameters of the heat transfer enhancement winglet, the overall heat transfer factor of the ventilation pipe with the rectangular heat transfer enhancement winglet is first calculated according to the wind speed condition, and the influence of the structural parameters of the heat transfer enhancement winglet on the overall heat transfer performance is given in the form of an isogram, and finally the length-diameter ratio and the attack angle are selected according to the required compensation overall heat transfer factor PEC.

[0029] As a preferred scheme of the present application, in step S3, the overall heat transfer factor PEC, the length-diameter ratio L / D l / D and the attack angle β of the heat transfer enhancement winglet are calculated by the following expressions:

[0030] ;

[0031] ;

[0032] ;

[0033] ;

[0034] ;

[0035] In the formula, V m is the average wind speed in the pipe, with the unit of m / s; Nu 0 and f 0 represent the Nusselt number and the friction coefficient of the ventilation pipe without the heat transfer enhancement winglet, respectively, Nu 0 and f 0 are both dimensionless quantities; Nu and f represent the Nusselt number and the friction coefficient of the ventilation pipe with the heat transfer enhancement winglet, respectively, Nu and f are both dimensionless quantities; Re is the Reynolds number, which is a dimensionless quantity; D is the inner diameter of the ventilation pipe, with the unit of m; L is the length of the ventilation pipe, with the unit of m; Pr is the Prandtl number, which is a dimensionless quantity; l is the length of the heat transfer enhancement winglet, with the unit of m; β is the attack angle of the heat transfer enhancement winglet, with the unit of °; represents PEC is a ternary function about the average wind speed V m , the length-diameter ratio L / D l / D and the attack angle β of the heat transfer enhancement winglet.

[0036] As a preferred embodiment of the present invention, in step S4, 4-12 of the enhanced heat exchange fins are attached at equal intervals to the inner wall of the ventilation duct.

[0037] As a preferred embodiment of the present invention, the reinforced heat exchange wing is made of flexible material, and the height of the reinforced heat exchange wing is set to within 3mm and the thickness is set to within 1mm, which helps to reduce pressure loss.

[0038] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0039] This invention achieves the goal of regulating the lateral differences in the cooling performance of the ventilation duct subgrade by uniformly leveling the convective heat transfer intensity within the ductwork, thereby improving the uniformity of the embankment's ambient temperature, enhancing engineering safety, and playing an important role in protecting permafrost and maintaining the stability of permafrost embankments. Attached Figure Description

[0040] Figure 1 This is a graph showing the variation of the convective heat transfer coefficient along the inner wall of a typical ventilation duct.

[0041] Figure 2 This is a structural layout diagram of rectangular reinforced heat exchange fins on the cross-section of the ventilation duct;

[0042] Figure 3 This is a structural layout diagram of rectangular reinforced heat exchange fins along the axial direction of the ventilation duct;

[0043] Figure 4 This is a schematic diagram of the rectangular reinforced heat exchange winglet in Example 1;

[0044] Figure 5 This is a schematic diagram of the structure of a ventilation duct base with reinforced heat exchange fins;

[0045] Figure 6 It is a contour map of the parameter design method for aspect ratio and angle of attack under target PEC;

[0046] Figure 7 This is a technical roadmap of the design process in Example 1;

[0047] Figure 8 This is a schematic diagram of another type of reinforced heat exchange winglet;

[0048] Figure 9 This is a schematic diagram of another type of reinforced heat exchange wing.

[0049] Icons: 1-Ventilation duct; 2-Enhanced heat exchange fins. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings.

[0051] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0052] Embodiment

[0053] A method for regulating the lateral difference of the cooling performance of a permafrost pipeline ventilation roadbed, as shown in Figures 1-7 , comprises the following steps:

[0054] Step one, monitor the climate conditions of the area where the constructed permafrost area roadbed is located, summarize the wind speed, air temperature, ground surface and roadbed two-sided temperature and other factors within a year, fully consider the sunny and shady slope effect on both sides of the roadbed, and model and numerically calculate the ventilation pipe roadbed. On this basis, the pipe wall surface convective heat transfer coefficient h is derived, as shown in Figure 1 .

[0055] Step two, discard the points with negative convective heat transfer coefficient on both sides of the air inlet and air outlet of the ventilation pipe 1, and interpolate and fit the remaining points to obtain h = P(x) , record the maximum value of the convective heat transfer coefficient on the pipe wall h max and the corresponding position x 1 (close to the air inlet). The maximum value of the convective heat transfer coefficient on the pipe wall h max is taken as the convective heat transfer coefficient uniformization target in this embodiment h surf ( h surf is a positive number).

[0056] Step three, take x 1 as the reference, record the position of each point x 2、 x 3、 ……x n in the deep part of the pipe at a preset interval, such as 2m, and calculate the surface convective heat transfer coefficient h = P(x) of each point according to the fitting formula h 2、 h 3、 …… h n , wherein h max > h 2> h 3> h n , the subscript n only represents the number of different positions, which is a positive integer.

[0057] Step four, for x 2. x 3. ……x n The pipe wall is equipped with enhanced heat exchange fins 2 to compensate for the convective heat transfer intensity. After compensation, the convective heat transfer intensity reaches the following levels: h 2* PEC2, h 3* PEC3, ... h n* PEC n make them all equal to h surf (Right now h max ),Right now , ... PEC refers to the comprehensive heat transfer factor of the enhanced heat transfer wing 2, which is a dimensionless quantity and its full name is performance evaluation criterion.

[0058] After equipping the pipe with enhanced heat transfer fins 2, when the fluid passes over their surface, it will generate vortices around the fluid and along the main flow direction. Such vortices have been proven by existing technology to effectively increase the velocity gradient near the wall, thereby enhancing convective heat transfer. In this embodiment, the enhanced heat transfer fins 2 adopt a rectangular structure, which is simple and convenient for designing structural parameters. The design is based on the required PEC for each wall section and the local average wind speed. V m The required aspect ratio for designing and enhancing the heat exchange winglet 2 l / D and attack angle ;like Figures 2-4 As shown, in this embodiment, the length direction of the enhanced heat exchange wing 2 is set at a certain angle along the axis of the ventilation duct 1. When ventilation is carried out along the axial direction of the ventilation duct 1, the airflow will blow towards the enhanced heat exchange wing 2 at different angles and circulate around the surface of the enhanced heat exchange wing 2 at a certain angle, thereby producing different convective heat transfer effects. In this embodiment, the angle between the length direction of the enhanced heat exchange wing 2 and the axis of the ventilation duct is the angle of attack. β ,like Figure 3 , Figure 4 Specifically: The calculation method for the comprehensive heat transfer factor PEC of the enhanced heat transfer wing 2 can be expressed as follows:

[0059] ;

[0060] in, express PEC It's about average wind speed. V m Enhanced heat exchange winglet length-to-diameter ratiol / D and the angle of attack β . The average wind speed V m can be regarded as a constant, so the PEC can be degenerated into a bivariate function containing the aspect ratio l / D and the angle of attack β .

[0061] The PEC is calculated as follows:

[0062] ;

[0063] where Nu 0 and f 0 represent the Nusselt number and the friction factor of the ventilation duct without the heat transfer enhancement fin 2, respectively, Nu 0 and f 0 are dimensionless quantities; Nu and f represent the Nusselt number and the friction factor of the ventilation duct 1 with the heat transfer enhancement fin 2, respectively, Nu and f are dimensionless quantities.

[0064] The Nusselt number Nu 0 of the ventilation duct 1 without the heat transfer enhancement fin 2 can be estimated by the Gnielinski formula, which is expressed as:

[0065] ;

[0066] where Re is the Reynolds number, which is a dimensionless quantity, , V m is the average wind speed in the duct (in m / s), which is 3.0-6.0 m / s on the Qinghai-Tibet Plateau, and is greater in winter than in summer; D is the inner diameter of the ventilation duct (in m), which is 40 cm; v is the kinematic viscosity, which is about 2.7310-5m 2 / s. Therefore, 10 4 < Re <10 5 , which is fully developed turbulent flow.

[0067] The friction factor f 0 can be expressed by the Blasius correlation:

[0068] ;

[0069] The Prandtl number , the Prandtl number Pr is a dimensionless quantity. At an altitude of more than 4500 meters on the Qinghai-Tibet Plateau, the air specific heat at constant pressurec p = 1.004 kJ / kg, dynamic viscosity μ = 1.75 kg / ms, thermal conductivity = 0.02 W / m, derived Pr = 0.84. Single duct diameter D = 40 cm, duct length L = 2 m.

[0070] The heat transfer coefficient of the rectangular heat transfer enhancement fin 2 in the duct Nu and f can be expressed by the following experimental correlation:

[0071] ;

[0072] ;

[0073] wherein, V m is the average air velocity in the duct (unit: m / s), Re is the Reynolds number (dimensionless quantity), D is the inner diameter of the duct 1 (unit: m), L is the duct length of the duct 1 (unit: m), Pr is the Prandtl number (dimensionless quantity), l is the length of the heat transfer enhancement fin 2 (unit: m), β is the attack angle of the heat transfer enhancement fin 2 (unit: °).

[0074] In determining the structural parameters of the heat transfer enhancement fin 2, based on the above calculation method, the above correlation is edited by a subroutine, and the overall heat transfer factor of the duct 1 with the rectangular heat transfer enhancement fin 2 under different air velocity conditions is calculated in the main program, and the influence of the structural parameters of the heat transfer enhancement fin 2 on the overall heat transfer performance is given in the form of an isogram as shown in Figure 6 , and finally the appropriate length-diameter ratio and attack angle are determined according to the required overall heat transfer factor PEC by selecting the corresponding PEC isogram according to the required overall heat transfer factor PEC.

[0075] Further, the empirical formula corresponding to any isogram can be obtained by curve fitting:

[0076] When PEC = 1.05, the relationship between the length-diameter ratio l / D and the attack angle β is:

[0077] ;

[0078] When PEC = 1.10, the length-diameter ratio l / D and the attack angleβ The relationship is:

[0079] .

[0080] Step 5, in different locations x 1. x 2. x 3. ……x n Enhanced heat exchange fins 2 with corresponding structural parameters are installed on the pipe wall to compensate for the convective heat transfer intensity of different pipe wall sections.

[0081] Specifically, for example, such as Figure 2 , Figure 5 As shown, during installation, 4-12 reinforced heat exchange fins 2 are evenly spaced and attached to the inner wall of the ventilation duct 1. The reinforced heat exchange fins 2 are 3D printed using flexible materials such as nylon or resin. The height of the reinforced heat exchange fins 2 is set to within 3mm and the thickness to within 1mm to reduce pressure loss.

[0082] This embodiment divides the ventilation duct into segments and calculates the comprehensive heat transfer factor required to achieve a uniformity index at different duct segment locations based on the current convective heat transfer coefficient distribution. Then, based on the relationship between the comprehensive heat transfer factor and the structural parameters of the enhanced heat transfer wing 2, it rationally selects enhanced heat transfer wing 2 with specific structural parameters for placement at fixed locations. This compensates for the existing convective heat transfer coefficient at different duct segment locations, thereby controlling the lateral differences in the cooling performance of the duct ventilation roadbed and leveling the convective heat transfer intensity within the duct. The comprehensive heat transfer factor in this paper is used to characterize the overall heat transfer performance of the duct.

[0083] The method provided in this embodiment achieves the purpose of regulating the lateral differences in the cooling performance of the ventilation duct subgrade by uniformly leveling the convective heat transfer intensity within the ventilation duct subgrade, thereby improving the uniformity of the embankment's ambient temperature. This is beneficial for enhancing engineering safety and plays an important role in protecting permafrost and maintaining the stability of permafrost embankments.

[0084] As another possible implementation, the heat transfer fins used to enhance convective heat transfer can also adopt structural forms such as triangular prisms or fan-shaped cross sections, for example... Figure 8 , Figure 9 As shown, during installation, the height direction of the triangular prism is set along the axis of the ventilation duct, and the chord length direction of the fan-shaped cross-section is set along the axis of the ventilation duct to connect with the duct wall with a larger contact surface area, but this is not limited to the example above. Accordingly, the compensation capabilities of the enhanced heat exchange fins based on different structural forms for the overall heat exchange performance are different, and there are different correlations between their structural parameters and the overall heat exchange factor, but the leveling design concept provided in this embodiment can still be applied.

[0085] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for regulating the transverse difference of cold conduction performance of a permafrost pipeline ventilation embankment, characterized in that, Comprising the following steps: S1: Obtain the different positions in the length direction of the ventilation pipe x 1、 x 2、 x 3、 ……x n The convective heat transfer coefficient at the surface of the pipe wall h 1、 h 2、 h 3、 ……h n , n is a positive integer; the uniformization target of the convective heat transfer coefficient is h surf ; S2: Determining different positions of ventilation ducts x 1, x 2, x 3, ……x n The surface of the pipe wall to achieve the uniformization target of the convective heat transfer coefficient h surf The required comprehensive heat transfer factor respectively PEC 1, PEC 2, PEC 3, PEC n ; S3: the comprehensive heat transfer factor required by different positions of the ventilation pipe PEC determine the structural parameters of the enhanced heat transfer winglet; The reinforced heat exchange winglet adopts a rectangular structure, and the length-diameter ratio of the reinforced heat exchange winglet is determined according to the comprehensive heat exchange factor of the reinforced heat exchange winglet PEC The length-diameter ratio of the reinforced heat exchange winglet is determined according to the comprehensive heat exchange factor of the reinforced heat exchange winglet l / D And the attack angle β ; In determining the structural parameters of the heat transfer enhancement winglet, the overall heat transfer factor of the ventilation pipe with rectangular heat transfer enhancement winglet is calculated according to the wind speed condition, and the influence of the structural parameters of the heat transfer enhancement winglet on the overall heat transfer performance is given in the form of contour map, and finally the corresponding PEC contour is selected according to the required compensation overall heat transfer factor PEC to design the length-diameter ratio l / D and the angle of attack β ; The comprehensive heat transfer factor PEC, the length-diameter ratio of the enhanced heat transfer wing l / D and the angle of attack β is calculated by the following expression: ； ； ； ； ； wherein, V m is the average wind speed in the duct, with the unit of m / s; Nu 0 and f 0 represent the Nusselt number and friction factor of the ventilation duct without the heat transfer enhancement wing, respectively, Nu 0 and f 0 are both dimensionless quantities; Nu and f represent the Nusselt number and friction factor of the ventilation duct with the heat transfer enhancement wing, respectively, Nu and f are both dimensionless quantities; Re is the Reynolds number, which is a dimensionless quantity; D is the inner diameter of the ventilation duct, with the unit of m; L is the length of the ventilation duct, in m; Pr is the Prandtl number, a dimensionless quantity; l is the length of the heat transfer enhancing winglet, in m; β is the angle of attack of the heat transfer enhancing winglet, in °; denotes PEC is the average wind speed V m , the length-diameter ratio of the heat transfer enhancing winglet and the angle of attack β is a ternary function; S4: at different locations x 1、 x 2、 x 3、 ……x n The reinforced heat exchange wing with corresponding structure parameters is installed on the pipe wall, and the convection heat exchange intensity compensation is performed on the pipe wall segments at different positions of the ventilation pipe.

2. The method for regulating the transverse difference of permafrost pipeline ventilation embankment cooling performance according to claim 1, characterized in that, h surf Pick h 1. h 2. h 3. ……h n The maximum value in, when set h surf The corresponding position is x i , i For 1- n Any of the above, in step S4, during the installation of the enhanced heat exchange fins, x 1. x 2. x 3. ……x n Except x i Install heat exchange fins in locations other than those specified.

3. The method for regulating the transverse difference of permafrost pipeline ventilation embankment cold conduction performance according to claim 2, characterized in that, In step S1, the step of obtaining the heat exchange coefficient of the pipe wall surface at different positions comprises: S11: modeling the ventilation pipe roadbed according to the climate conditions of the region where the permafrost area roadbed is located; S12: Deriving the pipe wall surface convective heat transfer coefficient h A graph showing the relationship changes along the length direction of the ventilation pipe S13: On the relationship change diagram, the points with negative convective heat transfer coefficient on both sides of the air inlet and outlet of the ventilation pipe are discarded, and the remaining points are interpolated and fitted to obtain h= P x , and the maximum convective heat transfer coefficient near the air inlet on the pipe wall h max and the corresponding position x 1;​ S14: with x 1 as the reference, record the position of each point to the preset interval a to the deep part of the tube x 2, x 3, ……x n , and calculate the corresponding surface heat transfer coefficient of each point according to the fitting formula h= P(x) h 2, h 3, ……h n , wherein h max > h 2> h 3> h n ;​ In step S4, the heat transfer intensity compensation is performed on the wall of the pipe x 2、 x 3、 ……x n The small wings with corresponding structural parameters are installed on the wall of the pipe respectively to compensate the heat transfer intensity.

4. The method for regulating the transverse difference of permafrost pipeline vented embankment cold-conduction performance according to claim 3, characterized in that, The preset interval is a, and the value range of a is 0.5m≤a≤2m.

5. The method for regulating lateral difference of permafrost pipeline ventilation embankment cold-conduction performance according to claim 1, characterized in that, In step S2, x n The overall heat exchange factor required at the location PEC Is obtained by the following expression: , n is a positive integer.

6. The method for regulating lateral differences in cold-conducting performance of a permafrost pipeline vented embankment according to any of claims 1-5, characterized in that, In step S4, 4-12 said reinforced heat exchange winglets are pasted on the inner wall of the ventilation pipe at equal intervals.

7. The method for regulating the transverse difference of permafrost pipeline vented embankment cold-conduction performance according to claim 6, characterized in that, The reinforced heat exchange winglets are made of flexible materials, and the height of the reinforced heat exchange winglets is set to be within 3mm, and the thickness is set to be within 1mm.

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