CN115791872A - Heat transfer analysis method and system for ground heat exchanger - Google Patents
Heat transfer analysis method and system for ground heat exchanger Download PDFInfo
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- CN115791872A CN115791872A CN202310044303.2A CN202310044303A CN115791872A CN 115791872 A CN115791872 A CN 115791872A CN 202310044303 A CN202310044303 A CN 202310044303A CN 115791872 A CN115791872 A CN 115791872A
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Abstract
The invention belongs to the technical field of geothermal energy utilization, and particularly relates to a heat transfer analysis method and system for an underground pipe heat exchanger. The invention can analyze the sample soil, the transverse soil and the lower soil respectively, thereby reducing the use of various sensors, ensuring the accuracy of the analysis result while reducing the damage probability of the sensors without real-time operation, and simultaneously combining the calculation of the comprehensive heat loss of the sample soil, the backfill material and the outer wall of the buried pipe and the calculation of the floating loss of the transverse soil and the lower soil, outputting the analysis result in time and enabling the heat at the input end of the buried pipe to be regulated and controlled in time.
Description
Technical Field
The invention belongs to the technical field of geothermal energy utilization, and particularly relates to a heat transfer analysis method and system for an underground pipe heat exchanger.
Background
The buried heat exchanger is usually a high-density polyethylene pipe or a polybutylene pipe, and heat exchange between the system and the ground is realized through the flow of circulating fluid in a closed buried pipe, so that the purposes of heating and cooling a building are realized, the heating effect in winter can be improved, and the power consumption of an air conditioning system in summer can be reduced.
The heat transfer analysis of the existing heat exchanger of the buried pipe is mostly carried out comprehensive analysis on all soil around the buried pipe, the mode needs a large number of sensors to monitor, when the humidity of the surrounding soil is found to change, the heat demand is regulated and controlled through regulating and controlling the heat of the input end of the buried pipe, but a large number of sensors need continuous work, meanwhile, the calculated amount needed by a large number of data acquisition is large, the sensors are deeply buried underground and have large damage probability, and then corresponding delay or large errors can be generated in the calculated result, so that the phenomenon that the analyzed result is not timely or inaccurate is caused.
Disclosure of Invention
The invention aims to provide a heat transfer analysis method and a heat transfer analysis system for a ground heat exchanger, which can reduce the use of various sensors, ensure the accuracy of analysis results, and simultaneously combine the analysis of comprehensive heat loss and floating loss to output the analysis results in time.
The technical scheme adopted by the invention is as follows:
a method of ground heat exchanger heat transfer analysis comprising:
acquiring heat parameters of an inner input end of the buried pipe and the wall thickness of the buried pipe;
acquiring the embedding depth of the buried pipe and the thickness of a backfill material on the outer side of the buried pipe, and acquiring the thickness of soil by taking the upper surface of the backfill material as a reference;
carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein at least five groups of sample soil are sampled on each layer of sample soil;
performing a heat conduction test on all the sample soil to obtain the heat conductivity coefficient of the sample soil;
inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material, and the heat conductivity coefficient and the thickness of the sample soil into a heat conduction model together to obtain comprehensive heat loss;
acquiring heat demand, calculating transverse heat loss and lower-layer heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower-layer heat loss as floating loss;
acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat to a trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe, comparing the fluctuation degree with the standard fluctuation degree, and judging whether the fluctuation degree of the heat of the outer wall of the buried pipe exceeds the standard according to a comparison result;
if so, judging that the humidity of the sample soil, the transverse soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the transverse soil and the lower soil and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat at the input end of the buried pipe is kept constantly input.
In a preferred scheme, when the sample soil is sampled, the sampling comprises transverse sampling and longitudinal sampling, wherein when the transverse sampling is carried out, the adjacent sample soil is not connected with each other, and when the longitudinal sampling is carried out, the adjacent sample soil is connected end to end.
In a preferred embodiment, the step of sampling the soil layer by layer according to the soil thickness to obtain a plurality of groups of sample soils includes:
obtaining the thickness of soil, and carrying out equal division treatment to obtain a plurality of first-level stratified soils;
taking the junction of the adjacent first-level layered soil as a reference to perform offset sampling to obtain check soil;
acquiring the average humidity of the checking soil, and comparing the average humidity of the adjacent checking soil to obtain humidity deviation;
acquiring a humidity deviation threshold value, and comparing the humidity deviation threshold value with the humidity deviation amount;
if the humidity deviation value is larger than the humidity deviation threshold value, carrying out re-layering treatment on the first-level layered soil corresponding to the checking soil;
and if the humidity deviation value is less than or equal to the humidity deviation threshold value, indicating that the first-level layered soil corresponding to the checking soil meets the sampling standard, and calibrating the first-level layered soil to be sample soil.
In a preferred embodiment, the step of performing a re-layering treatment on the first-level layered soil corresponding to the verification soil includes:
acquiring humidity values of an upper layer and a lower layer of the checking soil;
substituting the humidity values of the upper layer and the lower layer of the checking soil into a pre-estimation model to obtain the humidity change rate of the checking soil;
taking the soil humidity at the junction of the first-level stratified soil as a reference, and adding and summing the soil humidity and the humidity deviation threshold to obtain a stratified reference value;
and inputting the humidity change rate and the layering reference value into a layering model to obtain the layering depth, layering the first-level layered soil corresponding to the checking soil according to the layering depth to obtain second-level layered soil, and calibrating the second-level layered soil into sample soil.
In a preferred embodiment, the step of performing the thermal conductivity test on all the sample soils to obtain the thermal conductivity of the sample soils includes:
inputting rated heat by taking the lower surface of the sample soil as a reference surface
And obtaining the thickness, the heat conduction area and the temperature difference of all the sample soils, and inputting the thicknesses, the heat conduction areas and the temperature differences into a heat conduction coefficient calculation formula together with the rated heat to obtain the heat conduction coefficients of all the sample soils.
In a preferred embodiment, the step of inputting the wall thickness of the buried pipe, the thermal conductivity and the thickness of the backfill material, and the thermal conductivity and the thickness of the sample soil into a thermal conductivity model together to obtain a comprehensive heat loss includes:
obtaining a heat conduction formula from the heat conduction model;
inputting the wall thickness and the heat conductivity coefficient of the buried pipe, the backfill material and the sample soil into a heat conduction formula together to obtain comprehensive heat loss;
wherein, the backfill material is selected from a material similar to the sample soil heat conduction material.
In a preferred embodiment, the step of obtaining the heat of the outer wall of the buried pipe in real time and inputting the heat to the trend change model to obtain the undulation degree of the heat of the outer wall of the buried pipe includes:
constructing an acquisition period of the heat of the outer wall of the buried pipe, and constructing a plurality of equidistant acquisition nodes according to the acquisition period;
acquiring the heat of the outer wall of the buried pipe below each acquisition node;
acquiring a trend function from the trend change model;
and inputting the outer wall heat of the buried pipes below the plurality of acquisition nodes into a trend function together to obtain the fluctuation degree of the outer wall heat of the buried pipes, wherein the outer wall heat of the buried pipes substituted into the trend function is continuous and is not equal to each other.
In a preferred embodiment, the step of recalculating the integrated heat loss amount of the sample soil according to the changed soil humidity after determining that the humidity of the sample soil, the lateral soil and the lower soil is increased or decreased includes:
acquiring the fluctuation degree of the heat of the outer wall of the buried pipe and the humidity of the sample soil;
if the humidity of the sample soil is not changed, the humidity of the transverse soil and the humidity of the lower soil are increased or decreased, and the heat of the input end of the buried pipe is calculated according to the fluctuation of the heat of the outer wall of the buried pipe;
if the humidity of the sample soil is changed, recalculating the comprehensive heat loss of the sample soil;
and when the heat fluctuation degree of the outer wall of the buried pipe reaches the standard heat fluctuation degree, keeping the heat at the input end of the buried pipe to be constantly input.
The invention also provides a heat transfer analysis system of the ground heat exchanger, which is applied to the heat transfer analysis method of the ground heat exchanger and comprises the following steps:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring heat parameters of an internal input end of the buried pipe and the wall thickness of the buried pipe;
the second acquisition module is used for acquiring the burying depth of the buried pipe and the thickness of a backfill material on the outer side of the buried pipe, and acquiring the soil thickness by taking the upper surface of the backfill material as a reference;
the sampling module is used for sampling soil in a layering manner according to the soil thickness to obtain a plurality of groups of sample soil, wherein at least five groups of sample soil are sampled in each layer;
the test module is used for carrying out heat conduction test on all the sample soil to obtain the heat conductivity coefficient of the sample soil;
the first calculation module is used for inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material, and the heat conductivity coefficient and the thickness of the sample soil into a heat conductivity model together to obtain comprehensive heat loss;
the second calculation module is used for acquiring heat demand, calculating transverse heat loss and lower-layer heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower-layer heat loss as floating loss;
the judging module is used for acquiring the outer wall heat of the buried pipe in real time, inputting the outer wall heat to the trend change model to obtain the outer wall heat fluctuation degree of the buried pipe, comparing the outer wall heat fluctuation degree with the standard heat fluctuation degree, and judging whether the outer wall heat fluctuation degree of the buried pipe exceeds the standard according to a comparison result;
if so, judging that the humidity of the sample soil, the transverse soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the transverse soil and the lower soil and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat at the input end of the buried pipe is kept constantly input.
And, a borehole heat exchanger heat transfer analysis apparatus comprising:
at least one processor;
and a memory communicatively coupled to the at least one processor;
wherein the memory stores a computer program executable by the at least one processor to enable the at least one processor to perform the borehole heat exchanger heat transfer analysis method described above.
The invention has the technical effects that:
the invention can analyze the sample soil, the transverse soil and the lower soil respectively, thereby reducing the use of various sensors, ensuring the accuracy of the analysis result while reducing the damage probability of the sensors without real-time operation, and simultaneously combining the calculation of the comprehensive heat loss of the sample soil, the backfill material and the outer wall of the buried pipe and the calculation of the floating loss of the transverse soil and the lower soil, outputting the analysis result in time and enabling the heat at the input end of the buried pipe to be regulated and controlled in time.
Drawings
FIG. 1 is a flow chart of a method provided by an embodiment of the present invention;
fig. 2 is a block diagram of a system provided by an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures of the present invention are described in detail below.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as specifically described herein, and it will be appreciated by those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the present invention and that the present invention is not limited by the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one preferred embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Referring to fig. 1 and 2, the present invention provides a method for analyzing heat transfer of a ground heat exchanger, comprising:
s1, acquiring heat parameters of an inner input end of a buried pipe and the wall thickness of the buried pipe;
s2, acquiring the embedding depth of the buried pipe and the thickness of a backfill material on the outer side of the buried pipe, and acquiring the thickness of soil by taking the upper surface of the backfill material as a reference;
s3, carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein at least five groups of sample soil are sampled in each layer;
s4, conducting heat conduction tests on all sample soils to obtain the heat conduction coefficients of the sample soils;
s5, inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material, and the heat conductivity coefficient and the thickness of the sample soil into a heat conduction model together to obtain comprehensive heat loss;
s6, acquiring heat demand, calculating transverse heat loss and lower-layer heat loss by combining comprehensive heat loss and input end heat, and calibrating the transverse heat loss and the lower-layer heat loss as floating loss;
s7, acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat to the trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe, comparing the fluctuation degree with the standard fluctuation degree, and judging whether the fluctuation degree of the heat of the outer wall of the buried pipe exceeds the standard or not according to a comparison result;
if so, judging that the humidity of the sample soil, the transverse soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the transverse soil and the lower soil and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat at the input end of the buried pipe keeps constant input.
As described in the above steps S1-S7, the buried pipe ground source heat pump system uses soil as a heat source or heat sink, and is composed of a heat pump unit and a set of buried heat exchangers buried underground, the buried heat exchangers are usually high-density polyethylene pipes or polybutylene pipes, heat exchange between the system and the ground is realized by circulating fluid flowing in the closed buried pipes, as the buried pipes are buried underground, corresponding heat loss is inevitably generated in the process of heat transfer, the embodiment conducts stratified sampling on the soil above the buried pipes according to the buried depth of the buried pipes, so as to obtain a plurality of sets of sample soils, and then measures and calculates the heat conductivity coefficient of the sample soils, thereby realizing the purpose of stratified analysis on the soil above the buried pipes, so that the generated heat loss is more accurate, furthermore, the wall thickness of the buried pipes and the backfill materials around the buried pipes can also generate heat loss, the comprehensive heat loss is calculated by combining the heat loss of the sample soil, so that the heat loss generated by the heat conduction of the buried pipe to the ground can be determined, of course, the corresponding heat loss can be generated on the side and the lower part of the buried pipe and is consistent with the upper part of the buried pipe, the heat conducted to the ground can be directly influenced by the floating loss, after the required heat is determined, the heat at the input end of the buried pipe can be obtained by reversely pushing the comprehensive heat loss and the floating loss, and due to the influence of underground water, the soil humidity of the sample soil, the transverse soil and the soil at the lower layer can be changed due to the influence of the underground water, so that the corresponding changes of the comprehensive heat loss and the floating loss can be caused, in the embodiment, the heat of the outer wall of the buried pipe is collected in real time, a value trend change model is input for real-time measurement and calculation, and then the real-time comparison with the standard heat fluctuation degree is carried out, whether the fluctuation degree of the heat of the outer wall of the buried pipe exceeds the standard or not is judged, so that whether the heat of the input end of the buried pipe is changed or not is determined, and therefore the sufficient heat support can be stably provided for the ground is guaranteed.
In a preferred embodiment, sampling the sample soil comprises transverse sampling and longitudinal sampling, wherein when the transverse sampling is carried out, the adjacent sample soils are not connected with each other, and when the longitudinal sampling is carried out, the adjacent sample soils are connected end to end.
In the above, when the sample soil is transversely collected, the heights of the adjacent sample soil are consistent, the thicknesses of the collected sample soil are also consistent, and when the sample soil is sampled, equidistant sampling is carried out based on the distribution route of the buried pipe, specific conditions are determined, and detailed limitation is not added, and when the sample soil is longitudinally sampled, the adjacent sample soil is connected end to end, so that the heat conductivity above the buried pipe can be more thoroughly measured, and the comprehensive heat loss above the buried pipe can be conveniently measured and calculated subsequently.
In a preferred embodiment, the step of sampling the soil in layers according to the soil thickness to obtain a plurality of groups of sample soils comprises:
s301, obtaining the thickness of soil, and carrying out equal division treatment to obtain a plurality of first-level layered soils;
s302, performing offset sampling by taking the junction of adjacent first-level stratified soil as a reference to obtain check soil;
s303, acquiring the average humidity of the check soil, and comparing the average humidity of the adjacent check soil to obtain the humidity deviation amount;
s304, acquiring a humidity deviation threshold, and comparing the humidity deviation threshold with a humidity deviation amount;
if the humidity deviation value is larger than the humidity deviation threshold value, re-layering the first-level layered soil corresponding to the verified soil;
and if the humidity deviation value is less than or equal to the humidity deviation threshold value, indicating that the first-level stratified soil corresponding to the verified soil meets the sampling standard, and calibrating the first-level stratified soil as sample soil.
As described in the above steps S301 to S304, when the soil above the buried pipe is sampled in layers, the soil thickness above the buried pipe is determined, and then the soil thickness is divided equally based on the soil thickness, so as to obtain a plurality of first-level layered soils, and then the boundary between adjacent first-level layered soils is subjected to the migration processing as the reference, so as to obtain the check soil, which aims to check the soil humidity of the first-level layered soils, so as to determine whether the first-level layered soils can be directly determined as the sample soil, and the determination process is performed based on the humidity deviation threshold and the humidity deviation amount of the check soil, wherein the humidity deviation amount is the deviation value of the average humidity of the first-level layered soils and the check soil, so as to reduce the evaluation error of the sample soil, and for the first-level layered soils with the humidity deviation value greater than the humidity deviation threshold, the re-layering processing is performed, so as to ensure the accuracy of the heat conductivity of each first-level layered soil measured and calculated.
In a preferred embodiment, the step of performing a re-stratification process on the first-level stratified soil corresponding to the calibration soil comprises:
s305, acquiring humidity values of an upper layer and a lower layer of check soil;
s306, substituting the humidity values of the upper layer and the lower layer of the check soil into the estimation model to obtain the humidity change rate of the check soil;
s307, taking the soil humidity at the junction of the first-level layered soil as a reference, and adding and summing the soil humidity and a humidity deviation threshold value to obtain a layered reference value;
s308, inputting the humidity change rate and the layering reference value into a layering model to obtain the layering depth, layering the first-level layered soil corresponding to the checking soil according to the layering depth to obtain second-level layered soil, and calibrating the second-level layered soil to be sample soil.
As described in the foregoing steps S305 to S308, when determining the check soil, soil with the same thickness above and below the adjacent first-level layered soil is used, and when re-layering the first-level layered soil corresponding to the check soil, the humidity values of the upper layer and the lower layer of the check soil are determined first, and then input into the estimation model, and the humidity change rate of the check soil is calculated, where an objective function in the estimation model is:
in the formula (I), wherein,
indicating the rate of change of the moisture of the check soil,
represents the upper layer humidity value of the checking soil,
indicating the lower layer humidity value of the check soil,
the thickness of the soil is shown and checked, and then the formula is used
A stratification reference value is obtained, wherein,
a value representing a layering reference value is indicated,
representing the soil moisture value at the junction of the adjacent first-level stratified soil,
and expressing a humidity deviation threshold value, and then inputting the humidity change rate and a layering reference value into a standard function in a layering model together, wherein the standard function is as follows:
in the formula (I), wherein,
and (3) expressing the layering depth of the checking soil, and carrying out secondary layering on the primary layered soil according to the layering depth to obtain secondary layered soil, and calibrating the secondary layered soil into sample soil.
In a preferred embodiment, the step of performing a thermal conductivity test on all sample soils to obtain the thermal conductivity of the sample soils comprises:
s401, inputting rated heat by taking the lower surface of the sample soil as a reference surface
S402, obtaining the thicknesses, heat conduction areas and temperature differences of all sample soils, and inputting the thicknesses, heat conduction areas and temperature differences into a heat conduction coefficient calculation formula together with rated heat to obtain the heat conduction coefficients of all sample soils.
As described in the above steps S401 to S402, the calculation formula of the thermal conductivity coefficient is:
in the formula (I), wherein,
which represents the coefficient of thermal conductivity of the material,
based on the formula, the heat conductivity coefficients of a plurality of sample soils can be measured one by one, and then the heat conductivity coefficients of a plurality of sample soils with the same depth are averaged, so that the heat conductivity coefficient of the sample soil with each depth above the buried pipe can be obtained.
In a preferred embodiment, the step of inputting the wall thickness of the buried pipe, the thermal conductivity and the thickness of the backfill material, and the thermal conductivity and the thickness of the sample soil into the thermal conductivity model together to obtain the comprehensive heat loss comprises:
s501, acquiring a heat conduction formula from a heat conduction model;
s502, inputting the wall thickness and the heat conductivity coefficient of the buried pipe, the backfill material and the sample soil into a heat conduction formula together to obtain comprehensive heat loss;
wherein, the backfill material is selected from the material similar to the sample soil heat conduction material.
As described in the above steps S501 to S502, the heat conduction formula is:
in the formula, R represents the comprehensive heat loss amount,
indicating the thermal conductivity of the outer wall of the buried pipe, the backfill material and the sample soil,
indicating the heat conducting area of the outer wall of the buried pipe, the backfill material and the sample soil,
indicating buried pipe external wall, backfill material and sampleThe temperature difference of the soil is measured by the temperature difference,
the thicknesses of the outer wall of the underground pipe, the backfill material and the sample soil are shown, and based on the thicknesses, the comprehensive heat loss of the outer wall of the underground pipe, the backfill material and the sample soil can be determined.
In a preferred embodiment, the step of obtaining the heat of the outer wall of the buried pipe in real time and inputting the heat to the trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe comprises:
s701, constructing an acquisition period of heat of the outer wall of the buried pipe, and constructing a plurality of equidistant acquisition nodes according to the acquisition period;
s702, acquiring the heat of the outer wall of the buried pipe below each acquisition node;
s703, acquiring a trend function from the trend change model;
s704, the outer wall heat of the underground pipes under the multiple collection nodes is input into the trend function together, and the fluctuation degree of the outer wall heat of the underground pipes is obtained, wherein the outer wall heat of the underground pipes substituted into the trend function is continuous and different from each other.
As described in the foregoing steps S701 to S704, when heat is input into the underground pipe, the heat of the outer wall of the underground pipe correspondingly fluctuates, in this embodiment, a manner of obtaining the heat of the outer wall of the underground pipe in real time is adopted to determine the fluctuation degree of the heat of the outer wall, so as to determine whether to change the heat at the input end of the underground pipe subsequently, so that the heat conducted to the ground can be relatively constant, wherein a trend function in the trend change model is:
in the formula, K represents the fluctuation degree of the heat of the outer wall of the buried pipe, m represents the number of the collection nodes,
the heat of the outer wall of the buried pipe in the interval of 1-m is represented, the fluctuation degree of the heat of the outer wall of the buried pipe can be obtained based on the formula, and then the fluctuation degree is compared with the standard heat fluctuation degree, and the condition that the standard heat fluctuation degree is not exceeded indicates that the fluctuation degree of the outer wall of the buried pipe is not exceededThe heat at the input end of the buried pipe can be continuously input, otherwise, the change of the soil humidity of the sample soil, the transverse soil or the lower soil is indicated, and then the comprehensive heat loss and the floating loss need to be recalculated according to the steps, so that the heat demand can be kept to be constant.
In a preferred embodiment, the step of recalculating the integrated heat loss amount of the sample soil according to the changed soil humidity, after determining that the humidity of the sample soil, the lateral soil and the lower soil is increased or decreased, comprises:
s705, acquiring the fluctuation degree of the heat of the outer wall of the buried pipe and the humidity of sample soil;
if the humidity of the sample soil is not changed, the humidity of the transverse soil and the humidity of the lower soil are increased or decreased, and the heat of the input end of the buried pipe is calculated according to the fluctuation of the heat of the outer wall of the buried pipe;
if the humidity of the sample soil changes, recalculating the comprehensive heat loss of the sample soil;
and S706, if the heat fluctuation degree of the outer wall of the buried pipe reaches the standard heat fluctuation degree, keeping the heat input at the input end of the buried pipe constant.
As described in the above steps S705-S706, whether the humidity of the sample soil changes or not is a determining factor for determining whether to recalculate the comprehensive heat loss of the sample soil, and whether the influence of the groundwater or the influence of the heat overflowing from the buried pipe may cause the humidity of the sample soil, the lateral soil and the lower soil to change, and the change of the humidity thereof also correspondingly affects the heat value of the outer wall of the buried pipe.
The invention also provides a heat transfer analysis system of the ground heat exchanger, which is applied to the heat transfer analysis method of the ground heat exchanger and comprises the following steps:
the first acquisition module is used for acquiring the heat parameter of the inner input end of the buried pipe and the wall thickness of the buried pipe;
the second acquisition module is used for acquiring the embedding depth of the buried pipe and the thickness of the backfill material outside the buried pipe, and acquiring the thickness of the soil by taking the upper surface of the backfill material as a reference;
the sampling module is used for sampling the soil layer by layer according to the soil thickness to obtain a plurality of groups of sample soils, wherein at least five groups of sample soils are sampled in each layer of sample soils;
the test module is used for carrying out heat conduction tests on all sample soils to obtain the heat conductivity coefficient of the sample soils;
the first calculation module is used for inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material and the heat conductivity coefficient and the thickness of the sample soil into the heat conduction model together to obtain comprehensive heat loss;
the second calculation module is used for acquiring the heat demand, calculating the transverse heat loss and the lower-layer heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower-layer heat loss as floating loss;
the judging module is used for acquiring the outer wall heat of the buried pipe in real time, inputting the outer wall heat to the trend change model to obtain the outer wall heat fluctuation degree of the buried pipe, comparing the outer wall heat fluctuation degree with the standard heat fluctuation degree, and judging whether the outer wall heat fluctuation degree of the buried pipe exceeds the standard according to a comparison result;
if so, judging that the humidity of the sample soil, the transverse soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the transverse soil and the lower soil and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat at the input end of the buried pipe keeps constant input.
The method comprises the steps that the collection of heat inside the buried pipe and the collection of sample soil, transverse soil and lower soil transmitted to the sample soil can be achieved through a temperature sensor, the wall thickness of the buried pipe, the backfill material and the thickness of the sample soil can be measured through a measuring tool when the buried pipe is buried, the use of the measuring tool is not limited, the humidity value of the sample soil can be monitored through a humidity sensor, the judgment condition related to a judgment module and the output of the result can be nested step by step through the if 8230, the else algorithm and the aim of adjusting the heat at the input end of the buried pipe according to the heat demand is achieved.
And, a borehole heat exchanger heat transfer analysis apparatus comprising:
at least one processor;
and a memory communicatively coupled to the at least one processor;
wherein the memory stores a computer program executable by the at least one processor, the computer program being executable by the at least one processor to enable the at least one processor to perform the borehole heat exchanger heat transfer analysis method described above.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, apparatus, article, or method. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of another identical element in a process, apparatus, article, or method comprising the element.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention. Structures, devices, and methods of operation not specifically described or illustrated herein are generally practiced in the art without specific recitation or limitation.
Claims (10)
1. A heat transfer analysis method for a ground heat exchanger is characterized by comprising the following steps: the method comprises the following steps:
acquiring heat parameters of an inner input end of the buried pipe and the wall thickness of the buried pipe;
acquiring the embedding depth of the buried pipe and the thickness of a backfill material on the outer side of the buried pipe, and acquiring the thickness of soil by taking the upper surface of the backfill material as a reference;
carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein at least five groups of sample soil are sampled on each layer of sample soil;
performing a heat conduction test on all the sample soil to obtain the heat conductivity coefficient of the sample soil;
inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material, and the heat conductivity coefficient and the thickness of the sample soil into a heat conduction model together to obtain comprehensive heat loss;
acquiring heat demand, calculating transverse heat loss and lower-layer heat loss by combining the comprehensive heat loss and the input end heat, and calibrating the transverse heat loss and the lower-layer heat loss as floating loss;
acquiring the outer wall heat of the buried pipe in real time, inputting the outer wall heat to a trend change model to obtain the outer wall heat fluctuation degree of the buried pipe, comparing the outer wall heat fluctuation degree with the standard heat fluctuation degree, and judging whether the outer wall heat fluctuation degree of the buried pipe exceeds the standard or not according to a comparison result;
if yes, judging that the humidity of the sample soil, the transverse soil and the lower layer soil is increased or decreased, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the transverse soil and the lower layer soil and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat at the input end of the buried pipe is kept constantly input.
2. A method of heat transfer analysis for an inground heat exchanger according to claim 1 wherein: sample during the sample soil, including horizontal sample and vertical sample, wherein, during horizontal sample, each other does not meet between the adjacent sample soil, and during vertical sample, end to end between the adjacent sample soil.
3. A method of heat transfer analysis for an inground heat exchanger according to claim 1 wherein: the step of carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soils comprises the following steps:
obtaining the thickness of soil, and carrying out equal division treatment to obtain a plurality of first-level layered soils;
taking the junction of the adjacent first-level layered soil as a reference to perform offset sampling to obtain check soil;
acquiring the average humidity of the checking soil, and comparing the average humidity of the adjacent checking soil to obtain humidity deviation;
acquiring a humidity deviation threshold value, and comparing the humidity deviation threshold value with the humidity deviation amount;
if the humidity deviation value is larger than the humidity deviation threshold value, carrying out re-layering treatment on the first-level layered soil corresponding to the checking soil;
and if the humidity deviation value is less than or equal to the humidity deviation threshold value, indicating that the first-level stratified soil corresponding to the checking soil meets the sampling standard, and calibrating the first-level stratified soil as sample soil.
4. A method of heat transfer analysis for a ground heat exchanger according to claim 1, wherein: the step of carrying out re-layering treatment on the first-level layered soil corresponding to the checking soil comprises the following steps:
acquiring humidity values of an upper layer and a lower layer of the checking soil;
substituting the humidity values of the upper layer and the lower layer of the checking soil into a pre-estimation model to obtain the humidity change rate of the checking soil;
taking the soil humidity at the junction of the first-level stratified soil as a reference, and adding and summing the soil humidity and the humidity deviation threshold to obtain a stratified reference value;
and inputting the humidity change rate and the layering reference value into a layering model to obtain a layering depth, layering the primary layered soil corresponding to the checking soil according to the layering depth to obtain secondary layered soil, and calibrating the secondary layered soil to be sample soil.
5. A method of heat transfer analysis for an inground heat exchanger according to claim 1 wherein: the step of performing a thermal conductivity test on all the sample soils to obtain the thermal conductivity of the sample soils comprises:
inputting rated heat by taking the lower surface of the sample soil as a reference surface
And obtaining the thickness, the heat conduction area and the temperature difference of all the sample soils, and inputting the thicknesses, the heat conduction areas and the temperature differences into a heat conduction coefficient calculation formula together with the rated heat to obtain the heat conduction coefficients of all the sample soils.
6. A method of heat transfer analysis for a ground heat exchanger according to claim 1, wherein: the step of inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material, and the heat conductivity coefficient and the thickness of the sample soil into a heat conduction model together to obtain the comprehensive heat loss comprises the following steps:
obtaining a heat conduction formula from the heat conduction model;
inputting the wall thickness and the heat conductivity coefficient of the buried pipe, the backfill material and the sample soil into a heat conduction formula together to obtain comprehensive heat loss;
wherein, the backfill material is selected from a material similar to the sample soil heat conduction material.
7. A method of heat transfer analysis for a ground heat exchanger according to claim 1, wherein: the step of acquiring the heat of the outer wall of the buried pipe in real time and inputting the heat to a trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe comprises the following steps:
constructing an acquisition period of the heat of the outer wall of the buried pipe, and constructing a plurality of equidistant acquisition nodes according to the acquisition period;
acquiring the heat of the outer wall of the buried pipe below each acquisition node;
acquiring a trend function from the trend change model;
and inputting the outer wall heat of the buried pipes below the plurality of acquisition nodes into a trend function together to obtain the fluctuation degree of the outer wall heat of the buried pipes, wherein the outer wall heat of the buried pipes substituted into the trend function is continuous and is not equal to each other.
8. A method of heat transfer analysis for an inground heat exchanger according to claim 1 wherein: the step of recalculating the comprehensive heat loss amount of the sample soil according to the changed soil humidity by judging that the humidity of the sample soil, the horizontal soil and the lower soil is increased or decreased, includes:
acquiring the heat fluctuation degree of the outer wall of the buried pipe and the humidity of the sample soil;
if the humidity of the sample soil is not changed, indicating that the humidity of the transverse soil and the humidity of the lower layer soil are increased or decreased, and calculating the heat of the input end of the buried pipe according to the fluctuation of the heat of the outer wall of the buried pipe;
if the humidity of the sample soil changes, recalculating the comprehensive heat loss of the sample soil;
when the heat fluctuation degree of the outer wall of the buried pipe reaches the standard heat fluctuation degree, the heat at the input end of the buried pipe is kept constantly input.
9. A heat transfer analysis system for a ground heat exchanger, which is applied to the heat transfer analysis method for the ground heat exchanger of any one of claims 1 to 8, and is characterized in that: the method comprises the following steps:
the first acquisition module is used for acquiring the heat parameter of the inner input end of the buried pipe and the wall thickness of the buried pipe;
the second acquisition module is used for acquiring the embedding depth of the buried pipe and the thickness of a backfill material outside the buried pipe, and acquiring the thickness of soil by taking the upper surface of the backfill material as a reference;
the sampling module is used for sampling soil layer by layer according to the soil thickness to obtain a plurality of groups of sample soil, wherein at least five groups of sample soil are sampled in each layer of sample soil;
the test module is used for carrying out heat conduction test on all the sample soil to obtain the heat conductivity coefficient of the sample soil;
the first calculation module is used for inputting the wall thickness of the buried pipe, the heat conductivity coefficient and the thickness of the backfill material, and the heat conductivity coefficient and the thickness of the sample soil into a heat conductivity model together to obtain comprehensive heat loss;
the second calculation module is used for acquiring heat demand, calculating transverse heat loss and lower-layer heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower-layer heat loss as floating loss;
the judging module is used for acquiring the outer wall heat of the buried pipe in real time, inputting the outer wall heat to the trend change model to obtain the outer wall heat fluctuation degree of the buried pipe, comparing the outer wall heat fluctuation degree with the standard heat fluctuation degree, and judging whether the outer wall heat fluctuation degree of the buried pipe exceeds the standard according to a comparison result;
if yes, judging that the humidity of the sample soil, the transverse soil and the lower layer soil is increased or decreased, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the transverse soil and the lower layer soil and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat at the input end of the buried pipe is kept constantly input.
10. A heat transfer analysis apparatus for a ground heat exchanger, comprising: the method comprises the following steps:
at least one processor;
and a memory communicatively coupled to the at least one processor;
wherein the memory stores a computer program executable by the at least one processor to enable the at least one processor to perform the method of borehole heat exchanger heat transfer analysis of any one of claims 1 to 8.
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