CN112307666B - Method for determining thermal resistance of ground heat exchanger based on geological stratification - Google Patents

Method for determining thermal resistance of ground heat exchanger based on geological stratification Download PDF

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CN112307666B
CN112307666B CN202011336188.9A CN202011336188A CN112307666B CN 112307666 B CN112307666 B CN 112307666B CN 202011336188 A CN202011336188 A CN 202011336188A CN 112307666 B CN112307666 B CN 112307666B
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heat exchanger
ground heat
pipe
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buried pipe
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张长兴
王新杰
王煜升
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Shandong University of Science and Technology
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    • G06—COMPUTING; CALCULATING OR COUNTING
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    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/08—Fluids
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    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/14—Pipes
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    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/08—Thermal analysis or thermal optimisation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Abstract

The invention discloses a method for determining thermal resistance of a ground heat exchanger based on geological stratification. The method comprises the steps of establishing a heat transfer model of the ground heat exchanger based on geological stratification by utilizing finite element simulation software, dividing a calculation region of the heat transfer model of the ground heat exchanger by utilizing a free tetrahedral unstructured grid, dispersing a non-isothermal pipeline flow heat transfer equation and a solid heat transfer equation of the heat transfer model of the ground heat exchanger into a difference equation by utilizing a finite volume method, solving the difference equation by utilizing a second-order windward format to obtain the temperature field distribution condition of the heat transfer model of the ground heat exchanger, calculating the average temperature of internal fluid and the temperature of pipe walls of U-shaped buried pipes at all the burial depths, calculating the heat exchange quantity and the thermal resistance value of the ground heat exchanger in all soil layers, and determining the thermal resistance value of the ground heat exchanger based on the geological stratification by integrating the thermal resistance value of the ground heat exchanger at all the burial depths in the burial depth direction. The method is efficient and convenient, improves the calculation accuracy of the thermal resistance, and meets the actual engineering requirements.

Description

Method for determining thermal resistance of ground heat exchanger based on geological stratification
Technical Field
The invention relates to the technical field of vertical buried pipe ground source heat pumps, in particular to a method for determining thermal resistance of a ground heat exchanger based on geological stratification.
Background
The ground heat exchanger is used as a key component of a ground source heat pump system, and the design of the ground heat exchanger is very important for improving the operation efficiency of the ground source heat pump system. The heat resistance of the heat exchanger of the ground heat exchanger is an important factor of the design of the heat exchanger, and the accurate value of the heat exchanger needs to be determined by combining the actual geological stratification condition in engineering.
Finite Element Method (FEM) is a commonly used numerical Method for solving approximate solution of partial differential equation boundary value problem with high efficiency. When the method is used for solving, the whole continuous area is discretized and decomposed into a finite number of units serving as finite elements, and an error function reaches the minimum value and generates a stable solution through a variational method. Finite element methods comprise all possible methods that relate simple equations over small regions of each finite element and use them to estimate complex equations over larger regions.
The finite element has the characteristics of high calculation precision and suitability for various complex shapes, thereby becoming an effective engineering analysis means. Therefore, the physical model is established based on the finite element method, the thermal resistance of the buried pipe heat exchanger under the layered condition is obtained by using a numerical method, and the method is simple and accurate and better accords with the engineering practice.
Disclosure of Invention
The invention aims to provide a method for determining the thermal resistance of a ground heat exchanger based on geological stratification, so as to more conveniently and effectively obtain the thermal resistance of the ground heat exchanger under the stratified condition.
The invention adopts the following technical scheme:
a method for determining the thermal resistance of a ground heat exchanger based on geological stratification specifically comprises the following steps:
step 1, constructing a ground heat exchanger by using finite element simulation software, wherein the ground heat exchanger comprises a drilling hole, a backfill material and a U-shaped buried pipe, one end of the U-shaped buried pipe is provided with a liquid inlet pipe, the other end of the U-shaped buried pipe is provided with a liquid outlet pipe, soil layers where the ground heat exchanger is located are divided, a ground heat exchanger heat transfer model based on geological stratification is established, the structural parameters, the calculation area, the calculation time and the boundary conditions of the ground heat exchanger heat transfer model are set, the initial conditions of each soil layer and the U-shaped buried pipe are set, the pipe orifice of the liquid inlet pipe of the U-shaped buried pipe is set as the temperature and pressure inlet of the ground heat exchanger heat transfer model, and the pipe orifice of the liquid outlet pipe of the U-shaped pipe is set as the temperature and pressure outlet of the ground heat exchanger heat transfer model;
step 2, based on a near pipe wall encryption principle, adopting free tetrahedral unstructured grids to perform grid division on a heat transfer model calculation area of the buried pipe heat exchanger, and determining the number of the grids by performing independence test on the divided grids;
step 3, dispersing a non-isothermal pipeline flow heat transfer equation and a solid heat transfer equation of the heat transfer model of the ground heat exchanger into a difference equation by using a finite volume method, and solving the dispersed difference equation by adopting a second-order windward format to obtain the temperature field distribution condition of the heat transfer model of the ground heat exchanger;
step 4, determining the change rule of the temperature of the fluid in the U-shaped buried pipe in the heat transfer model of the buried pipe heat exchanger along with the buried depth of the U-shaped buried pipe according to the temperature field distribution condition of the heat transfer model of the buried pipe heat exchanger, and calculating the average temperature value of the fluid in the U-shaped buried pipe at each buried depth and the wall surface temperature of the borehole wall of the buried pipe heat exchanger;
the average temperature value of the fluid in the U-shaped buried pipe is as follows:
Tf,i＝(Tin,i+Tout,i)/2 (1)
in the formula, Tf,iThe average temperature value of the fluid in the U-shaped buried pipe at the buried depth i is represented by K; t isin,iThe temperature value of the fluid in the U-shaped buried pipe liquid inlet pipe at the buried depth i is represented by K; t isout,iThe temperature value of the fluid in the liquid outlet pipe of the U-shaped buried pipe at the buried depth i is expressed in K;
step 5, calculating the layered heat exchange quantity Q of the ground heat exchanger at each burial depth according to the temperature field distribution condition of the heat transfer model of the ground heat exchangeriAs shown in formula (2):
Qi＝cm((Tin,i-Tin,i+1)+(Tout,i+1-Tout,i)) (2)
in the formula, QiRepresenting the layered heat exchange quantity Q of the buried pipe heat exchanger at the buried depth iiThe unit is J/s; c represents the mass heat capacity of fluid in the U-shaped buried pipe of the ground heat exchanger, and the unit is J/(kg & K); m represents the mass flow of fluid in the U-shaped buried pipe of the ground heat exchanger, and the unit is kg/s; t isin,iThe temperature of the fluid on the top surface of the liquid inlet pipe of the U-shaped buried pipe at the buried depth i is expressed in K; t isin,i+1The temperature of the fluid at the bottom surface of the liquid inlet pipe of the U-shaped buried pipe at the buried depth i is represented by K; t isout,i+1The temperature of the fluid on the top surface of the liquid outlet pipe of the U-shaped buried pipe at the buried depth i is expressed in K; t isout,iThe temperature of the fluid at the bottom surface of the liquid outlet pipe of the U-shaped buried pipe at the buried depth i is represented by K;
and calculating the heat exchange amount of the ground heat exchanger in the ground heat exchanger heat transfer model at each burial depth by combining the thickness of the soil layer at each burial depth, wherein the formula (3) is as follows:
Figure BDA0002797205230000021
in the formula, qL,iThe heat exchange quantity of the ground heat exchanger at the burial depth i is represented, and the unit is W/m; hiRepresents the thickness of the soil layer at the burial depth i, and the unit is m;
and 6, calculating the thermal resistance value of the ground heat exchanger at each burial depth according to the heat exchange quantity of the ground heat exchanger at each burial depth, wherein the formula (4) is as follows:
Figure BDA0002797205230000031
in the formula, Rb,iThe thermal resistance value of the ground heat exchanger at the buried depth i is expressed in the unit of m.K/W; t isb,iThe wall surface temperature of the borehole wall of the buried pipe heat exchanger at the buried depth i is represented and is expressed in K;
and 7, integrating the thermal resistance values of the ground heat exchangers at the burial depths in the burial depth direction to determine the thermal resistance values of the ground heat exchangers based on geological stratification, wherein the calculation formula is as follows:
Figure BDA0002797205230000032
in the formula, RbThe thermal resistance value of the ground heat exchanger is expressed, and the unit is m.K/W; rb,iThe thermal resistance value of the ground heat exchanger at the burial depth i is shown and is expressed in K; h represents the buried depth of the ground heat exchanger and is expressed in m.
Preferably, in step 1, the U-shaped buried pipe is made of a high density polyethylene HDPE material.
Preferably, in the step 1, the structural parameters of the heat transfer model of the ground heat exchanger include a drilling radius, a drilling depth, an inner diameter of the U-shaped buried pipe, an outer diameter of the U-shaped buried pipe, a soil mass radius, a soil mass thickness, a wall thickness of the U-shaped buried pipe and a pipe interval.
Preferably, in the step 1, a calculation region of a heat transfer model of the ground heat exchanger is set according to an actual engineering region; setting the calculation time of a heat transfer model of the buried pipe heat exchanger according to the engineering technical specification of a ground source heat pump system; setting the boundary conditions of the top surface and the side surface and the bottom surface of a heat transfer model of the ground heat exchanger as constant temperature boundary conditions and adiabatic boundary conditions; setting initial temperature, temperature gradient and thermophysical parameters of each soil layer; setting the initial condition inside the U-shaped buried pipe to be constant pressure, and setting the initial temperature and the temperature gradient of the U-shaped buried pipe.
Preferably, in the step 2, based on a near-pipe-wall encryption principle, the calculation region has dense meshing at the U-shaped buried pipe of the near-ground heat exchanger heat transfer model, and has sparse meshing at the U-shaped buried pipe of the far-ground heat exchanger heat transfer model.
The invention has the following beneficial effects:
the invention provides a method for determining the thermal resistance of a ground heat exchanger based on geological stratification based on a finite element method, which comprises the steps of establishing a heat transfer model of the ground heat exchanger based on geological stratification, stratifying a soil layer by combining actual geological conditions, researching the relation between the temperature of fluid inside a U-shaped buried pipe of the ground heat exchanger and the buried depth of the ground heat exchanger, determining the heat exchange quantity of the ground heat exchanger at different buried depths, and calculating the thermal resistance value of the ground heat exchanger; the method utilizes a finite element method to calculate the layered heat exchange process of the ground heat exchanger, efficiently and conveniently obtains the thermal resistance value of the ground heat exchanger under the condition of soil layering, and lays a theoretical foundation for realizing the accurate design of the ground heat exchanger group.
Drawings
Fig. 1 is a schematic diagram of a heat transfer model of a ground heat exchanger based on geological stratification, wherein fig. 1(a) is a schematic diagram of a horizontal section of the ground heat exchanger, and fig. 1(b) is a schematic diagram of soil stratification of the heat transfer model of the ground heat exchanger.
FIG. 2 is a schematic diagram of the calculation region meshing of the heat transfer model of the ground heat exchanger.
Figure 3 is a temperature distribution diagram of fluid inside the U-shaped buried pipe.
Figure 4 is an average temperature profile of the fluid inside the U-shaped buried pipe.
FIG. 5 is a schematic diagram of the heat exchange process of the ground heat exchanger.
FIG. 6 is the borehole wall temperature of borehole heat exchangers at different depths of burial.
Figure 7 shows the amount of heat exchange in a borehole heat exchanger at different depths of burial.
Figure 8 is a graph of the thermal resistance of a borehole heat exchanger at different depths of burial.
Detailed Description
The invention will be further described with reference to the following detailed description and drawings:
a method for determining the thermal resistance of a ground heat exchanger based on geological stratification specifically comprises the following steps:
step 1, constructing a ground heat exchanger by using finite element simulation software, wherein the ground heat exchanger comprises a drill hole, backfill materials and a U-shaped buried pipe, the backfill materials are filled between the drill hole and the U-shaped buried pipe, the U-shaped buried pipe is made of high-density polyethylene HDPE materials, one end of the U-shaped buried pipe is a liquid inlet pipe, the other end of the U-shaped buried pipe is a liquid outlet pipe, and fluid flows into the U-shaped buried pipe from the liquid inlet pipe and then flows out of the liquid outlet pipe.
Dividing the soil layer where the ground heat exchanger is located into four layers according to the geological condition of the actual work area, and setting the thermophysical parameters of each soil layer, including the heat conductivity coefficient lambda and the heat capacity CsAs shown in table 1.
TABLE 1 thermophysical parameters of each soil layer
Figure BDA0002797205230000041
According to the constructed ground heat exchanger and the soil layer division result, a heat transfer model of the ground heat exchanger based on geological stratification is established, and structural parameters of the heat transfer model of the ground heat exchanger are set, wherein the drilling radius r is setb0.06m, the drilling depth H of 51m and the inner diameter d of the U-shaped buried pipein0.026m, U-shaped buried pipe external diameter doutThe diameter of the soil body is 0.032m, the radius r of the soil body is 60m, the thickness L of the soil body is 62m, the thickness delta w of the pipe wall of the U-shaped buried pipe is 0.003m, and the distance D between the U-shaped buried pipes is 0.06 m; fluid medium in U-shaped buried pipeIs water.
Setting a calculation region of a heat transfer model of the ground heat exchanger according to an actual engineering region; setting the calculation time t of the heat transfer model of the ground heat exchanger as 100h and the time interval as 0.5h according to the engineering technical specification of the ground source heat pump system; the heating power of the ground heat exchanger is 5kW, and the circulation flow of the medium in the U-shaped buried pipe is 0.24 kg/s; setting the boundary conditions of the top surface and the side surface and the bottom surface of a heat transfer model of the ground heat exchanger as constant temperature boundary conditions and adiabatic boundary conditions, as shown in FIG. 1 (b); setting the initial temperature of each soil layer to be 15.37 ℃, wherein the temperature gradient between each soil layer and the U-shaped buried pipe is 0.024 ℃/m; the U-shaped buried pipe is internally provided with a constant pressure, the pipe orifice of the liquid inlet pipe of the U-shaped buried pipe is a temperature and pressure inlet of a heat transfer model of the ground heat exchanger, and the pipe orifice of the liquid outlet pipe of the U-shaped buried pipe is a temperature and pressure outlet of the heat transfer model of the ground heat exchanger.
Step 2, based on a near pipe wall encryption principle, adopting free tetrahedral unstructured grids to perform grid division on a heat transfer model calculation region of the buried pipe heat exchanger, wherein the grid division at a U-shaped buried pipe of the heat transfer model of the buried pipe heat exchanger in the calculation region is dense, and the grid division at a position of the heat transfer model of the buried pipe heat exchanger away from the calculation region is sparse, as shown in fig. 2; and (3) carrying out independence test on the divided grids, so that the influence of the number of the grids on the finite element simulation calculation result is less than 5%, and the minimum unit of the grids is determined to be 0.48, the growth rate is 1.4, and the total number of the grids is 143063.
And 3, coupling the heat transfer model of the ground heat exchanger by adopting a non-isothermal pipeline flow heat transfer equation and a solid heat transfer equation, dispersing the non-isothermal pipeline flow heat transfer equation and the solid heat transfer equation of the heat transfer model of the ground heat exchanger into a difference equation by using a finite volume method, solving the dispersed difference equation by adopting a second-order windward format, and obtaining the temperature field distribution condition of the heat transfer model of the ground heat exchanger when the calculation is finished (the calculation time is 100 h).
Step 4, determining a change rule of the temperature of the fluid inside the U-shaped buried pipe in the heat transfer model of the ground heat exchanger along with the buried depth of the U-shaped buried pipe according to the temperature field distribution condition of the heat transfer model of the ground heat exchanger, as shown in fig. 3, calculating an average temperature value of the fluid inside the U-shaped buried pipe at each buried depth by using a formula (1), as shown in fig. 4, calculating the average temperature value of the fluid inside the U-shaped buried pipe at each buried depth in the embodiment, then calculating the wall surface temperature of the borehole wall of the ground heat exchanger at each buried depth, and as shown in fig. 5, calculating the wall surface temperature of the borehole wall of the ground heat exchanger at each buried depth in the embodiment.
Step 5, calculating the layered heat exchange quantity Q of the ground heat exchanger at each burial depth by using a formula (2) according to the temperature field distribution condition of the heat transfer model of the ground heat exchanger and combining the heat exchange process of the ground heat exchanger shown in the figure 6i(ii) a And (3) calculating the heat exchange quantity of the ground heat exchanger in the heat transfer model of the ground heat exchanger at each burial depth by combining the thickness of each soil layer, wherein the heat exchange quantity of the ground heat exchanger at different burial depths is shown in figure 7.
And 6, calculating the thermal resistance value of the ground heat exchanger at each burial depth by using a formula (4) according to the heat exchange quantity of the ground heat exchanger at each burial depth and combining the temperatures of the drill hole walls of the ground heat exchangers at different burial depths shown in the figure 7, wherein the thermal resistance value of the ground heat exchanger at different burial depths is shown in the figure 8.
And 7, integrating the thermal resistance values of the ground heat exchangers at the burial depths in the burial depth direction, calculating the thermal resistance value of the ground heat exchanger based on geological stratification by using a formula (5), and determining the thermal resistance value R of the ground heat exchangerbIt was 0.128 (m.K)/W.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.

Claims (5)

1. A method for determining the thermal resistance of a ground heat exchanger based on geological stratification is characterized by comprising the following steps:
step 1, constructing a ground heat exchanger by using finite element simulation software, wherein the ground heat exchanger comprises a drilling hole, a backfill material and a U-shaped buried pipe, one end of the U-shaped buried pipe is provided with a liquid inlet pipe, the other end of the U-shaped buried pipe is provided with a liquid outlet pipe, soil layers where the ground heat exchanger is located are divided, a ground heat exchanger heat transfer model based on geological stratification is established, the structural parameters, the calculation area, the calculation time and the boundary conditions of the ground heat exchanger heat transfer model are set, the initial conditions of each soil layer and the U-shaped buried pipe are set, the pipe orifice of the liquid inlet pipe of the U-shaped buried pipe is set as the temperature and pressure inlet of the ground heat exchanger heat transfer model, and the pipe orifice of the liquid outlet pipe of the U-shaped pipe is set as the temperature and pressure outlet of the ground heat exchanger heat transfer model;
step 2, based on a near pipe wall encryption principle, adopting free tetrahedral unstructured grids to perform grid division on a heat transfer model calculation area of the buried pipe heat exchanger, and determining the number of the grids by performing independence test on the divided grids;
step 3, dispersing a non-isothermal pipeline flow heat transfer equation and a solid heat transfer equation of the heat transfer model of the ground heat exchanger into a difference equation by using a finite volume method, and solving the dispersed difference equation by adopting a second-order windward format to obtain the temperature field distribution condition of the heat transfer model of the ground heat exchanger;
step 4, determining the change rule of the temperature of the fluid in the U-shaped buried pipe in the heat transfer model of the buried pipe heat exchanger along with the buried depth of the U-shaped buried pipe according to the temperature field distribution condition of the heat transfer model of the buried pipe heat exchanger, and calculating the average temperature value of the fluid in the U-shaped buried pipe at each buried depth and the wall surface temperature of the borehole wall of the buried pipe heat exchanger;
the average temperature value of the fluid in the U-shaped buried pipe is as follows:
Tf,i＝(Tin,i+Tout,i)/2 (1)
in the formula, Tf,iThe average temperature value of the fluid in the U-shaped buried pipe at the buried depth i is represented by K; t isin,iThe temperature value of the fluid in the U-shaped buried pipe liquid inlet pipe at the buried depth i is represented by K; t isout,iThe temperature value of the fluid in the liquid outlet pipe of the U-shaped buried pipe at the buried depth i is expressed in K;
step 5, calculating the layered heat exchange quantity Q of the ground heat exchanger at each burial depth according to the temperature field distribution condition of the heat transfer model of the ground heat exchangeriAs shown in formula (2):
Qi＝cm((Tin,i-Tin,i+1)+(Tout,i+1-Tout,i)) (2)
in the formula, QiRepresenting the layered heat exchange quantity Q of the buried pipe heat exchanger at the buried depth iiThe unit is J/s; c represents the mass heat capacity of fluid in the U-shaped buried pipe of the ground heat exchanger, and the unit is J/(kg & K); m represents the mass flow of fluid in the U-shaped buried pipe of the ground heat exchanger, and the unit is kg/s; t isin,iThe temperature of the fluid on the top surface of the liquid inlet pipe of the U-shaped buried pipe at the buried depth i is expressed in K; t isin,i+1The temperature of the fluid at the bottom surface of the liquid inlet pipe of the U-shaped buried pipe at the buried depth i is represented by K; t isout,i+1The temperature of the fluid on the top surface of the liquid outlet pipe of the U-shaped buried pipe at the buried depth i is expressed in K; t isout,iThe temperature of the fluid at the bottom surface of the liquid outlet pipe of the U-shaped buried pipe at the buried depth i is represented by K;
and calculating the heat exchange amount of the ground heat exchanger in the ground heat exchanger heat transfer model at each burial depth by combining the thickness of the soil layer at each burial depth, wherein the formula (3) is as follows:
Figure FDA0002797205220000021
in the formula, qL,iThe heat exchange quantity of the ground heat exchanger at the burial depth i is represented, and the unit is W/m; hiRepresents the thickness of the soil layer at the burial depth i, and the unit is m;
and 6, calculating the thermal resistance value of the ground heat exchanger at each burial depth according to the heat exchange quantity of the ground heat exchanger at each burial depth, wherein the formula (4) is as follows:
Figure FDA0002797205220000022
in the formula, Rb,iThe thermal resistance value of the ground heat exchanger at the buried depth i is expressed in the unit of m.K/W; t isb,iThe wall surface temperature of the borehole wall of the buried pipe heat exchanger at the buried depth i is expressed in unit ofK；
And 7, integrating the thermal resistance values of the ground heat exchangers at the burial depths in the burial depth direction to determine the thermal resistance values of the ground heat exchangers based on geological stratification, wherein the calculation formula is as follows:
Figure FDA0002797205220000023
in the formula, RbThe thermal resistance value of the ground heat exchanger is expressed, and the unit is m.K/W; rb,iThe thermal resistance value of the ground heat exchanger at the burial depth i is shown and is expressed in K; h represents the buried depth of the ground heat exchanger and is expressed in m.
2. The method of determining thermal resistance of a geological stratification based borehole heat exchanger as claimed in claim 1 wherein in step 1 the U-shaped borehole is formed from a high density polyethylene HDPE material.
3. The method for determining the thermal resistance of the ground heat exchanger based on geological stratification according to claim 1, wherein in the step 1, the structural parameters of the heat transfer model of the ground heat exchanger comprise a drilling hole radius, a drilling hole depth, an inner diameter of the U-shaped buried pipe, an outer diameter of the U-shaped buried pipe, a soil mass radius, a soil mass thickness, a wall thickness of the U-shaped buried pipe and a pipe spacing.
4. The method for determining the thermal resistance of the ground heat exchanger based on the geological stratification according to claim 1, characterized in that in the step 1, a calculation region of a heat transfer model of the ground heat exchanger is set according to an actual engineering region; setting the calculation time of a heat transfer model of the buried pipe heat exchanger according to the engineering technical specification of a ground source heat pump system; setting the boundary conditions of the top surface and the side surface and the bottom surface of a heat transfer model of the ground heat exchanger as constant temperature boundary conditions and adiabatic boundary conditions; setting initial temperature, temperature gradient and thermophysical parameters of each soil layer; setting the initial condition inside the U-shaped buried pipe to be constant pressure, and setting the initial temperature and the temperature gradient of the U-shaped buried pipe.
5. The method for determining the thermal resistance of the ground heat exchanger based on geological stratification according to claim 1, wherein in the step 2, the grid division at the U-shaped buried pipe of the heat transfer model of the ground heat exchanger in the calculation region is dense based on the near pipe wall encryption principle, and the grid division at the U-shaped buried pipe of the heat transfer model of the ground heat exchanger away from the calculation region is sparse.
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Citations (3)

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Publication number Priority date Publication date Assignee Title
CN107907564A (en) * 2017-11-07 2018-04-13 山东科技大学 A kind of definite method of ground thermal property parameter and vertical ground heat exchanger thermal resistance
CN111125921A (en) * 2019-12-27 2020-05-08 常州工学院 Method for rapidly and accurately realizing dynamic simulation of performance of vertical U-shaped ground heat exchanger
CN111488704A (en) * 2020-03-13 2020-08-04 中国电力科学研究院有限公司 Method and system for calculating external thermal resistance of calandria laid cable

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US20130049575A1 (en) * 2010-07-14 2013-02-28 Shunsuke Fujita Phosphor composite member, led device and method for manufacturing phosphor composite member

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107907564A (en) * 2017-11-07 2018-04-13 山东科技大学 A kind of definite method of ground thermal property parameter and vertical ground heat exchanger thermal resistance
CN111125921A (en) * 2019-12-27 2020-05-08 常州工学院 Method for rapidly and accurately realizing dynamic simulation of performance of vertical U-shaped ground heat exchanger
CN111488704A (en) * 2020-03-13 2020-08-04 中国电力科学研究院有限公司 Method and system for calculating external thermal resistance of calandria laid cable

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