CN115791872B - Heat transfer analysis method and system for buried pipe heat exchanger - Google Patents
Heat transfer analysis method and system for buried pipe heat exchanger Download PDFInfo
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- CN115791872B CN115791872B CN202310044303.2A CN202310044303A CN115791872B CN 115791872 B CN115791872 B CN 115791872B CN 202310044303 A CN202310044303 A CN 202310044303A CN 115791872 B CN115791872 B CN 115791872B
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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 a heat transfer analysis system for a buried pipe heat exchanger. According to the invention, the sample soil, the transverse soil and the lower soil can be respectively analyzed, so that the use of various sensors is reduced, the sensors do not need to run in real time, the damage probability of the sensors is reduced, the accuracy of analysis results can be ensured, and meanwhile, 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 are combined, so that the analysis results can be timely output, and the heat of the input end of the buried pipe can be timely regulated and controlled.
Description
Technical Field
The invention belongs to the technical field of geothermal energy utilization, and particularly relates to a heat transfer analysis method and a heat transfer analysis system for a buried pipe heat exchanger.
Background
The buried pipe ground source heat pump system uses soil as a heat source or heat sink, and consists of a heat pump unit and a group of buried heat exchangers buried underground, wherein the buried heat exchangers are usually high-density polyethylene pipes or polybutylene pipes, and heat exchange between the system and the ground is realized through the flow of circulating fluid in the closed underground buried pipes, so that the purposes of heating and cooling a building are realized, the winter heating effect is improved, and the power consumption of an air conditioning system in summer can be reduced.
The existing heat transfer analysis of the buried pipe heat exchanger is to comprehensively analyze all the soil around the buried pipe, a large number of sensors are needed to monitor in the mode, when the humidity of the soil around the buried pipe is found to change, the heat demand is regulated and controlled by regulating and controlling the heat of the input end of the buried pipe, but a large number of sensors need continuous work, meanwhile, the calculation amount needed by a large number of data acquisition is large, the probability of damage caused by the fact that the sensors are buried underground deeply is also large, and further, the corresponding delay or larger error of the calculation result can be caused, so that the phenomenon that the analysis result is not timely or accurate occurs is caused.
Disclosure of Invention
The invention aims to provide a heat transfer analysis method and a heat transfer analysis system for a buried pipe 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 timely output the analysis results.
The technical scheme adopted by the invention is as follows:
a heat transfer analysis method of a buried pipe heat exchanger comprises the following steps:
acquiring heat parameters of an input end in the buried pipe and the wall thickness of the buried pipe;
acquiring the embedding depth of the buried pipe and the thickness of backfill material outside the buried pipe, and acquiring the soil thickness by taking the upper surface of the backfill material as a reference;
performing layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein each layer of sample soil is at least sampled into five groups;
conducting heat conduction tests on all the sample soil to obtain the heat conduction coefficient of the sample soil;
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 are input into a heat conduction model together to obtain comprehensive heat loss;
acquiring heat demand, calculating transverse heat loss and lower heat loss by combining the comprehensive heat loss and the heat of an input end, and calibrating the transverse heat loss and the lower heat loss as floating loss;
acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat into 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 heat 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 horizontal soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the horizontal 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 of the input end of the buried pipe is kept to be input constantly.
In a preferred scheme, sampling the sample soil comprises transverse sampling and longitudinal sampling, wherein adjacent sample soil is not connected with each other in transverse sampling, and adjacent sample soil is connected end to end in longitudinal sampling.
In a preferred embodiment, the step of performing stratified sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil includes:
the soil thickness is obtained, and the soil is equally divided to obtain a plurality of first-level layered soil;
taking the junction of adjacent first-level layered soil as a reference to carry out offset sampling to obtain check soil;
acquiring the average humidity of the check soil, and comparing the average humidity of the adjacent check soil to obtain humidity deviation;
acquiring a humidity deviation threshold value and comparing the humidity deviation threshold value with the humidity deviation value;
if the humidity deviation value is larger than the humidity deviation threshold value, re-layering the first-level layered soil corresponding to the check soil;
and if the humidity deviation value is smaller than or equal to the humidity deviation threshold value, indicating that the first-level layered soil corresponding to the check soil accords with a sampling standard and is calibrated as sample soil.
In a preferred scheme, the step of re-layering the first-level layered soil corresponding to the verification soil comprises the following steps:
acquiring humidity values of an upper layer and a lower layer of the check soil;
substituting the humidity values of the upper layer and the lower layer of the verification soil into an estimated model to obtain the humidity change rate of the verification soil;
taking the soil humidity at the junction of the first-level layered soil as a reference, adding and summing the soil humidity with the humidity deviation threshold value to obtain a layered reference value;
and inputting the humidity change rate and the layering reference value into a layering model to obtain layering depth, layering the primary layering soil corresponding to the verification soil according to the layering depth to obtain secondary layering soil, and calibrating the secondary layering soil as sample soil.
In a preferred embodiment, the step of conducting a thermal conductivity test on all the sample soil to obtain a thermal conductivity coefficient of the sample soil includes:
taking the lower surface of the sample soil as a reference surface, and inputting rated heat
And acquiring the thickness, the heat conduction area and the temperature difference of all the sample soil, and then inputting the thickness, the heat conduction area and the temperature difference into a heat conduction coefficient calculation formula together with rated heat to obtain the heat conduction coefficients of all the sample soil.
In a preferred embodiment, the step of inputting the wall thickness of the buried pipe, the thermal conductivity coefficient and the thickness of the backfill material, and the thermal conductivity coefficient and the thickness of the sample soil into a thermal conductivity model together to obtain the integrated heat loss comprises the following steps:
acquiring a heat conduction formula from the heat conduction model;
the wall thickness and the heat conductivity coefficient of the buried pipe, the backfill material and the sample soil are input into a heat conduction formula together to obtain comprehensive heat loss;
wherein the backfill material is a material similar to the sample soil heat conducting 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 a trend change model to obtain the heat fluctuation 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 under each acquisition node;
obtaining a trend function from the trend change model;
and inputting the outer wall heat of the buried pipes under 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 between adjacent buried pipes.
In a preferred embodiment, the step of determining whether the humidity of the sample soil, the lateral soil, and the sub-soil increases or decreases, and recalculating the integrated heat loss of the sample soil according to the changed soil humidity comprises:
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 lower soil is increased or decreased, and calculating the heat of the input end of the buried pipe according to the fluctuation degree 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 when the heat fluctuation of the outer wall of the buried pipe reaches the standard heat fluctuation, keeping the heat of the input end of the buried pipe constant.
The invention also provides a heat transfer analysis system of the buried pipe heat exchanger, which is applied to the heat transfer analysis method of the buried pipe heat exchanger, and comprises the following steps:
the first acquisition module is used for acquiring heat parameters of an input end in 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 soil thickness by taking the upper surface of the backfill material as a reference;
the sampling module is used for carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein each layer of sample soil is used for sampling at least five groups;
the test module is used for conducting heat conduction tests on all the sample soil to obtain the heat conduction 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 the heat conductivity model together to obtain the comprehensive heat loss;
the second calculation module is used for acquiring heat demand, calculating transverse heat loss and lower heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower heat loss as floating loss;
the judging module is used for acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat into the trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe, comparing the fluctuation degree of the heat of the outer wall of the buried pipe with the fluctuation degree of the standard heat, 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 horizontal soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the horizontal 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 of the input end of the buried pipe is kept to be input constantly.
And, a buried pipe 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:
according to the invention, the sample soil, the transverse soil and the lower soil can be respectively analyzed, so that the use of various sensors is reduced, the sensors do not need to run in real time, the damage probability of the sensors is reduced, the accuracy of analysis results can be ensured, and meanwhile, 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 are combined, so that the analysis results can be timely output, and the heat of the input end of the buried pipe can be timely regulated and controlled.
Drawings
FIG. 1 is a flow chart of a method provided by an embodiment of the present invention;
fig. 2 is a system block diagram provided by an embodiment of the present invention.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present invention is not limited to the specific embodiments disclosed below.
Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be 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 invention provides a heat transfer analysis method of a buried pipe heat exchanger, which comprises the following steps:
s1, acquiring heat parameters of an input end inside a buried pipe and the wall thickness of the buried pipe;
s2, acquiring the embedding depth of the buried pipe and the thickness of the backfill material outside the buried pipe, and acquiring the soil thickness by taking the upper surface of the backfill material as a reference;
s3, performing stratified sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein each layer of sample soil is at least sampled to five groups;
s4, conducting heat conduction tests on all the sample soil to obtain the heat conduction coefficient of the sample soil;
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 heat loss by combining the comprehensive heat loss and the heat of an input end, and calibrating the transverse heat loss and the lower heat loss as floating loss;
s7, acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat into 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 fluctuation degree of the standard heat, 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 whether the humidity of the sample soil, the horizontal soil and the soil at the lower layer is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the horizontal soil and the soil at the lower layer and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat of the input end of the buried pipe is kept to be input constantly.
As described in the above steps S1-S7, the ground-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 group of buried heat exchangers buried underground, wherein the buried heat exchangers are usually high-density polyethylene pipes or polybutylene pipes, heat exchange between the system and the ground is realized through the flow of circulating fluid in the closed underground buried pipes, and due to the fact that the buried pipes are buried underground, corresponding heat loss is inevitably generated in the heat transfer process, the embodiment performs layered sampling on the soil above based on the buried depth of the buried pipes, so as to obtain a plurality of groups of sample soil, then the heat conductivity coefficients of the sample soil are measured, thereby realizing the purpose of layered analysis on the soil above the buried pipes, ensuring that the generated heat loss is more accurate, and the wall thickness of the buried pipes and backfill materials around the buried pipes also generate heat loss, the comprehensive heat loss is calculated by combining the heat loss of the sample soil, and the heat loss generated by the heat conduction of the buried pipe to the ground can be determined, of course, the side and the lower part of the buried pipe can generate corresponding heat loss which is consistent with the upper part of the buried pipe, the embodiment marks the heat loss as floating loss which directly affects the heat conducted to the ground, after the heat demand is determined, the heat of the input end of the buried pipe can be obtained by carrying out inverse pushing by combining the comprehensive heat loss and the floating loss, the soil humidity of the sample soil, the transverse soil and the lower soil can be changed due to the influence of the groundwater, thus the corresponding change of the comprehensive heat loss and the floating loss is also caused, the heat of the outer wall of the buried pipe is collected in real time in the embodiment, the input value trend change model is measured in real time, and then the standard heat fluctuation degree is compared in real time, and judging whether the heat fluctuation of the outer wall of the buried pipe exceeds the standard, so as to determine whether to change the heat of the input end of the buried pipe, thereby ensuring that enough heat support can be stably provided for the ground.
In a preferred embodiment, sampling the sample soil includes sampling laterally and sampling longitudinally, wherein adjacent sample soil is not connected to each other during sampling laterally, and adjacent sample soil is connected end to end during sampling longitudinally.
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, when the sample soil is sampled, equidistant sampling is carried out based on the distribution route of the buried pipe, and the sample soil is not limited in detail according to specific conditions, and when the sample soil is longitudinally sampled, the adjacent sample soil is connected end to end, so that the heat conductivity coefficient above the buried pipe can be measured in more detail, and the subsequent measurement of the comprehensive heat loss above the buried pipe is facilitated.
In a preferred embodiment, the step of stratified sampling the soil according to the soil thickness to obtain a plurality of groups of sample soil comprises:
s301, obtaining soil thickness, and performing equal division treatment to obtain a plurality of first-level layered soil;
s302, taking the junction of adjacent first-level layered soil as a reference to carry out offset sampling to obtain check soil;
s303, acquiring the average humidity of the check soil, and comparing the average humidity of adjacent check soil to obtain humidity deviation;
s304, acquiring a humidity deviation threshold value and comparing the humidity deviation threshold value with the humidity deviation value;
if the humidity deviation value is larger than the humidity deviation threshold value, re-layering the first-level layered soil corresponding to the check soil;
and if the humidity deviation value is smaller than or equal to the humidity deviation threshold value, the first-level layered soil corresponding to the check soil is indicated to accord with the sampling standard and is calibrated as sample soil.
As described in the above steps S301 to S304, when the soil above the buried pipe is subjected to the stratified sampling, the soil thickness above the buried pipe is first determined, then the aliquoting treatment is performed based on the determined soil thickness above the buried pipe, so as to obtain a plurality of first-stage stratified soil, then the deviation treatment is performed based on the boundary of the adjacent first-stage stratified soil, so as to obtain the check soil, the purpose of which is to check the soil humidity of the first-stage stratified soil, so as to determine whether the first-stage stratified soil 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-stage stratified soil and the check soil, so as to reduce the evaluation error of the sample soil, and the re-layering treatment is required for the first-stage stratified soil with the humidity deviation value greater than the humidity deviation threshold, so as to ensure the accuracy of the thermal conductivity coefficient of each first-stage stratified soil measured.
In a preferred embodiment, the step of re-layering the first-level layered soil corresponding to the check soil includes:
s305, acquiring humidity values of an upper layer and a lower layer of check soil;
s306, substituting humidity values of the upper layer and the lower layer of the verification soil into the pre-estimated model to obtain the humidity change rate of the verification 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 with 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 layering depth, layering the first-level layering soil corresponding to the verification soil according to the layering depth to obtain second-level layering soil, and calibrating the second-level layering soil as sample soil.
As described in the above steps S305-S308, when determining the verification soil, taking the soil with the same thickness above and below the adjacent first-level layered soil, when re-layering the first-level layered soil corresponding to the verification soil, determining the humidity values of the upper layer and the lower layer of the verification soil, and then inputting the humidity values into the pre-estimation model to calculate the humidity change rate of the verification soil, wherein the objective function in the pre-estimation model is as follows:
wherein->
Indicating the rate of change of the humidity of the check soil,
indicating the upper humidity value of the check soil, +.>
Indicating the value of the lower humidity of the check soil, +.>
Indicating the thickness of the check soil, and then according to the formula +.>
Determining a hierarchical reference value, wherein +_>
Indicates a layering reference value,/->
Represents soil moisture value at boundary of adjacent first-level layered soil,/->
And then the humidity change rate and the layering reference value are input into a standard function in the layering model, wherein the standard function is as follows: />
Wherein->
And (3) representing the layering depth of the check soil, and secondarily layering the primary layering soil according to the layering depth so as to obtain secondary layering soil, and calibrating the secondary layering soil as sample soil.
In a preferred embodiment, the step of conducting a thermal conductivity test on all sample soil to obtain a thermal conductivity coefficient of the sample soil comprises:
s401, taking the lower surface of the sample soil as a reference surface, and inputting rated heat
S402, acquiring the thickness, the heat conduction area and the temperature difference of all the sample soil, and then inputting the thickness, the heat conduction area and the temperature difference into a heat conduction coefficient calculation formula together with rated heat to obtain the heat conduction coefficients of all the sample soil.
As described in the above steps S401 to S402, the calculation formula of the thermal conductivity is:
wherein->
Indicating the heat conductivity +.>
For rated heat, A is the heat conduction area, dt represents the thickness of sample soil, dx represents the temperature difference between the upper layer and the lower layer of the sample soil, based on the temperature difference, the heat conduction coefficients of a plurality of sample soil can be calculated one by one, and then the heat conduction coefficients of a plurality of sample soil with the same depth are averaged to obtain the upper part of the buried pipeThermal conductivity of sample soil at each depth.
In a preferred embodiment, the steps 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 the heat conduction model together to obtain the comprehensive heat loss comprise the following steps:
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 a material similar to the sample soil heat conduction material.
As described in the above steps S501 to S502, the heat conduction formula is:
wherein R represents the total heat loss, ">
Indicating the thermal conductivity of the outer wall of the buried pipe, backfill material and sample soil +.>
Indicating the heat conduction area of the outer wall of the buried pipe, backfill material and sample soil +.>
Indicating the temperature difference of the outer wall of the buried pipe, backfill material and sample soil>
Representing the thickness of the outer wall of the buried pipe, the backfill material and the sample soil, based on which the combined heat loss of the outer wall of the buried 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 heat fluctuation of the outer wall of the buried pipe comprises the following steps:
s701, 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;
s702, acquiring the heat of the outer wall of the buried pipe under each acquisition node;
s703, obtaining a trend function from the trend change model;
s704, inputting the heat of the outer wall of the buried pipe under the plurality of acquisition nodes into a trend function together to obtain the fluctuation degree of the heat of the outer wall of the buried pipe, wherein the heat of the outer wall of the buried pipe substituted into the trend function is continuous and is different from each other.
As described in the above steps S701-S704, when heat is input into the buried pipe, the heat of the outer wall of the buried pipe will correspondingly have fluctuation, and in this embodiment, the method of acquiring the heat of the outer wall of the buried pipe in real time is adopted to determine whether the heat of the input end of the buried pipe needs to be changed later, so that the heat conducted to the ground can be relatively constant, where the trend function in the trend change model is as follows:
wherein K represents the fluctuation of the heat quantity of the outer wall of the buried pipe, m represents the number of acquisition nodes,/and>
the method comprises the steps of representing the heat of the outer wall of the buried pipe in the interval 1-m, obtaining the fluctuation degree of the heat of the outer wall of the buried pipe based on the formula, comparing the fluctuation degree with the standard heat fluctuation degree, and for the condition that the fluctuation degree of the standard heat is not exceeded, indicating that the heat of the input end of the buried pipe can be continuously input, otherwise, indicating that the humidity of the soil of sample soil, transverse soil or lower soil is changed, and further, recalculating the comprehensive heat loss and the floating loss according to the steps, so that the heat demand can be constantly output.
In a preferred embodiment, the step of determining whether the humidity of the sample soil, the lateral soil and the sub-soil increases or decreases, and re-calculating the total heat loss of the sample soil according to the changed soil humidity, comprises:
s705, obtaining the heat fluctuation degree of the outer wall of the buried pipe and the humidity of sample soil;
if the humidity of the sample soil is unchanged, the humidity of the transverse soil and the lower soil is increased or reduced, 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;
s706, when the heat fluctuation of the outer wall of the buried pipe reaches the standard heat fluctuation, the heat of the input end of the buried pipe is kept to be input constantly.
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 re-measure the integrated heat loss of the sample soil, whether the influence of groundwater or the influence of the heat of the overflow of the buried pipe may cause the humidity of the sample soil, the horizontal soil and the heat demand of the lower soil to change, and the humidity change thereof also affects the heat value of the outer wall of the buried pipe correspondingly, when the heat fluctuation of the outer wall of the buried pipe is too large, the humidity sensor may be started to obtain the humidity value of the sample soil, so as to determine whether the humidity of the sample soil changes, no separate humidity sensor is required to be configured to monitor the humidity values of the horizontal soil and the lower soil, the floating loss corresponding to the horizontal soil and the lower soil may be calculated in advance through experiments, the floating loss is obtained by subtracting the integrated heat loss and the heat demand from the heat at the input end of the buried pipe, and the humidity sensor monitoring the humidity value of the sample soil is only started when the heat fluctuation of the outer wall of the buried pipe is too large, without providing continuous power support, and the above steps may not be repeated for re-calculating the integrated heat loss of the sample soil.
The invention also provides a heat transfer analysis system of the buried pipe heat exchanger, which is applied to the heat transfer analysis method of the buried pipe heat exchanger, and comprises the following steps:
the first acquisition module is used for acquiring the heat parameters of the input end inside 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 soil thickness by taking the upper surface of the backfill material as a reference;
the sampling module is used for carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein each layer of sample soil is used for sampling at least five groups;
the test module is used for conducting heat conduction tests on all sample soil to obtain the heat conduction 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 the heat conduction model together to obtain the comprehensive heat loss;
the second calculation module is used for acquiring heat demand, calculating transverse heat loss and lower heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower heat loss as floating loss;
the judging module is used for acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat into the trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe, comparing the fluctuation degree of the heat with the fluctuation degree of the standard heat, and judging whether the fluctuation degree of the heat of the outer wall of the buried pipe exceeds the standard according to the comparison result;
if so, judging whether the humidity of the sample soil, the horizontal soil and the soil at the lower layer is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the horizontal soil and the soil at the lower layer and the heat of the input end of the buried pipe according to the changed soil humidity;
if not, the heat of the input end of the buried pipe is kept to be input constantly.
In the above, the heat in the buried pipe and the collection of the sample soil, the transverse soil and the soil under the soil can be realized by the temperature sensor, the wall thickness of the buried pipe, the backfill material and the thickness of the sample soil can be measured by the 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 by the humidity sensor, the judging conditions related to the judging module and the output of the result can be nested step by the if … … else algorithm, and the aim is to adjust the heat of the input end of the buried pipe according to the heat demand.
And, a buried pipe 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.
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 phrase "comprising one … …" does not exclude the presence of other like elements in a process, apparatus, article or method that comprises the element.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention. Structures, devices and methods of operation not specifically described and illustrated herein, unless otherwise indicated and limited, are implemented according to conventional means in the art.
Claims (10)
1. A heat transfer analysis method of a buried pipe heat exchanger is characterized by comprising the following steps of: comprising the following steps:
acquiring heat parameters of an input end in the buried pipe and the wall thickness of the buried pipe;
acquiring the embedding depth of the buried pipe and the thickness of backfill material outside the buried pipe, and acquiring the soil thickness by taking the upper surface of the backfill material as a reference;
performing layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein each layer of sample soil is at least sampled into five groups;
conducting heat conduction tests on all the sample soil to obtain the heat conduction coefficient of the sample soil;
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 are input into a heat conduction model together to obtain comprehensive heat loss;
acquiring heat demand, calculating transverse heat loss and lower heat loss by combining the comprehensive heat loss and the heat of an input end, and calibrating the transverse heat loss and the lower heat loss as floating loss;
acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat into 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 fluctuation degree of the standard heat, 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 horizontal soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the horizontal 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 of the input end of the buried pipe is kept to be input constantly.
2. A method of analyzing heat transfer of a borehole heat exchanger according to claim 1, wherein: and when sampling the sample soil, the method comprises transverse sampling and longitudinal sampling, wherein adjacent sample soil is not mutually connected during transverse sampling, and adjacent sample soil is connected end to end during longitudinal sampling.
3. A method of analyzing heat transfer of a borehole heat exchanger according to claim 1, wherein: the step of obtaining a plurality of groups of sample soil by sampling soil in a layered manner according to the soil thickness comprises the following steps:
the soil thickness is obtained, and the soil is equally divided to obtain a plurality of first-level layered soil;
taking the junction of adjacent first-level layered soil as a reference to carry out offset sampling to obtain check soil;
acquiring the average humidity of the check soil, and comparing the average humidity of the adjacent check soil to obtain humidity deviation;
acquiring a humidity deviation threshold value and comparing the humidity deviation threshold value with the humidity deviation value;
if the humidity deviation value is larger than the humidity deviation threshold value, re-layering the first-level layered soil corresponding to the check soil;
and if the humidity deviation value is smaller than or equal to the humidity deviation threshold value, indicating that the first-level layered soil corresponding to the check soil accords with a sampling standard and is calibrated as sample soil.
4. A method of heat transfer analysis for a borehole heat exchanger according to claim 3, wherein: the step of re-layering the first-level layered soil corresponding to the check soil comprises the following steps:
acquiring humidity values of an upper layer and a lower layer of the check soil;
substituting the humidity values of the upper layer and the lower layer of the verification soil into an estimated model to obtain the humidity change rate of the verification soil;
taking the soil humidity at the junction of the first-level layered soil as a reference, adding and summing the soil humidity with the humidity deviation threshold value to obtain a layered reference value;
and inputting the humidity change rate and the layering reference value into a layering model to obtain layering depth, layering the primary layering soil corresponding to the verification soil according to the layering depth to obtain secondary layering soil, and calibrating the secondary layering soil as sample soil.
5. A method of analyzing heat transfer of a borehole heat exchanger according to claim 1, wherein: the step of conducting heat conduction tests on all the sample soil to obtain the heat conduction coefficient of the sample soil comprises the following steps:
taking the lower surface of the sample soil as a reference surface, and inputting rated heat
And acquiring the thickness, the heat conduction area and the temperature difference of all the sample soil, and then inputting the thickness, the heat conduction area and the temperature difference into a heat conduction coefficient calculation formula together with rated heat to obtain the heat conduction coefficients of all the sample soil.
6. A method of analyzing heat transfer of a borehole 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:
acquiring a heat conduction formula from the heat conduction model;
the wall thickness and the heat conductivity coefficient of the buried pipe, the backfill material and the sample soil are input into a heat conduction formula together to obtain comprehensive heat loss;
wherein the backfill material is a material similar to the sample soil heat conducting material.
7. A method of analyzing heat transfer of a borehole heat exchanger according to claim 1, wherein: the step of obtaining 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 under each acquisition node;
obtaining a trend function from the trend change model;
and inputting the outer wall heat of the buried pipes under 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 between adjacent buried pipes.
8. A method of analyzing heat transfer of a borehole heat exchanger according to claim 1, wherein: and a step of calculating the comprehensive heat loss of the sample soil again according to the changed soil humidity if the humidity of the sample soil, the horizontal soil and the soil below is increased or decreased, wherein the step comprises the following steps of:
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 lower soil is increased or decreased, and calculating the heat of the input end of the buried pipe according to the fluctuation degree 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 when the heat fluctuation of the outer wall of the buried pipe reaches the standard heat fluctuation, keeping the heat of the input end of the buried pipe constant.
9. A heat transfer analysis system for a buried pipe heat exchanger, applied to the heat transfer analysis method for a buried pipe heat exchanger according to any one of claims 1 to 8, characterized in that: comprising the following steps:
the first acquisition module is used for acquiring heat parameters of an input end in 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 soil thickness by taking the upper surface of the backfill material as a reference;
the sampling module is used for carrying out layered sampling on the soil according to the soil thickness to obtain a plurality of groups of sample soil, wherein each layer of sample soil is used for sampling at least five groups;
the test module is used for conducting heat conduction tests on all the sample soil to obtain the heat conduction 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 the heat conductivity model together to obtain the comprehensive heat loss;
the second calculation module is used for acquiring heat demand, calculating transverse heat loss and lower heat loss by combining the comprehensive heat loss and the heat of the input end, and calibrating the transverse heat loss and the lower heat loss as floating loss;
the judging module is used for acquiring the heat of the outer wall of the buried pipe in real time, inputting the heat into the trend change model to obtain the fluctuation degree of the heat of the outer wall of the buried pipe, comparing the fluctuation degree of the heat of the outer wall of the buried pipe with the fluctuation degree of the standard heat, 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 horizontal soil and the lower soil is increased or reduced, and recalculating the comprehensive heat loss of the sample soil, the floating loss of the horizontal 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 of the input end of the buried pipe is kept to be input constantly.
10. The heat transfer analysis equipment of the buried pipe heat exchanger is characterized in that: comprising 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 borehole heat exchanger heat transfer analysis method as recited in any one of claims 1 to 8.
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| CN114781102A (en) * | 2022-03-14 | 2022-07-22 | 国网江苏省电力有限公司南京供电分公司 | Energy flow modeling method and application of urban comprehensive energy system |
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