A Design Method for Ground Source Heat Pump Buried Pipe Systems Based on Building Load Variation

Abstract

This invention relates to the field of ground source heat pump technology, specifically disclosing a design method for a ground source heat pump buried pipe system based on building load changes. The method includes: acquiring hourly dynamic load data of the building throughout the year, calculating the imbalance ratio of cold and hot loads to assess the risk of thermal imbalance; importing the dynamic load data into a three-dimensional heat transfer numerical calculation model of the buried pipe group, simulating and analyzing the evolution of the soil and rock temperature field during the design operation cycle; analyzing the temperature change trend and accumulated net heat gain of the soil and rock based on the simulation results, dividing the soil and rock region into a cold accumulation zone, a hot accumulation zone, and a thermal balance zone; setting up heat replenishment, heat dissipation, and heat exchange units in each zone, and formulating a multi-mode coordinated start-up and operation strategy. This invention solves the problems of traditional designs being unable to simulate long-term thermal imbalance and having poor system adaptability, achieving prediction and zoning of the soil and rock thermal field, and improving the long-term stability and robustness of the system through internal heat scheduling.

Description

Technical Field

[0001] This invention relates to the field of ground source heat pump technology, and specifically to a design method for a ground source heat pump buried pipe system based on building load changes. Background Technology

[0002] As a high-efficiency and renewable building energy supply technology, the core of the ground source heat pump system lies in the heat exchange between the ground pipe heat exchanger and the soil and rock mass to achieve heating and cooling of the building. In the traditional design of ground source heat pump systems, the ground pipe heat exchangers are usually evenly arranged according to the peak load of the building, and the drilling depth, number and spacing are calculated using fixed empirical formulas. This design method has obvious technical limitations and shortcomings when dealing with the dynamic changes in the building's heating and cooling load throughout the year: (1) High risk of thermal imbalance: The traditional design method cannot accurately simulate the cumulative effect of the dynamic load generated by the building during long-term operation on the temperature field of the soil and rock mass. Especially in areas where the cumulative amount of heating and cooling load is unbalanced, the long-term operation of the system will lead to an imbalance between heat absorption and heat release in the soil and rock mass, causing the soil and rock mass temperature to change continuously in one direction, resulting in heat accumulation or cold accumulation. This thermal imbalance phenomenon will directly lead to the gradual decline of the operating efficiency of the ground source heat pump system, and may even eventually fail due to the small heat exchange temperature difference, which seriously restricts the long-term stability and energy-saving effect of the system.

[0003] (2) Lack of adaptability and adjustment capability: Traditional design is a static and one-time investment. Once the system is built, its heat exchange capacity is fixed and cannot cope with changes in the building's future use function, adjustments in energy intensity, or changes in load characteristics caused by extreme weather years. Once the actual operating conditions deviate from the design expectations, the system lacks the means to actively intervene and adjust the heat balance, and cannot alleviate or eliminate the heat imbalance problem on its own, resulting in poor adaptability. Summary of the Invention

[0004] To address the above problems, this invention proposes a design method for a ground source heat pump buried pipe system based on building load changes. The specific technical solution is as follows: A design method for a ground source heat pump buried pipe system based on building load changes includes the following steps: Step S1: Obtain the hourly dynamic load data of the building throughout the year, statistically analyze the intensity-frequency distribution of cooling and heating loads and calculate the imbalance ratio of cooling and heating loads, and determine whether there is a risk of thermal imbalance. If so, proceed to step S2; otherwise, terminate the design process.

[0005] Step S2: Using the dynamic load data obtained in step S1 as input, import the pre-constructed three-dimensional heat transfer numerical calculation model of the buried pipe group, simulate and analyze the evolution law of the temperature field of the soil and rock mass around the buried pipe group during the design operation cycle, and generate a temperature change cloud map of the soil and rock mass.

[0006] Step S3: Based on the simulation results of step S2, determine the location of thermal imbalance by the temperature change trend, and determine whether the thermal imbalance type is cold accumulation or hot accumulation by combining the accumulated net heat gain, and then divide the rock and soil area into cold accumulation area, hot accumulation area and thermal balance area.

[0007] Step S4: Set up heating units, heat dissipation units, and heat exchange units in the cold accumulation zone, hot accumulation zone, and their boundary areas respectively, and formulate start-up and operation strategies for each thermal control unit.

[0008] Compared with existing technologies, the design method of ground source heat pump buried pipe system based on building load changes described in this invention has the following beneficial effects: 1. This invention obtains the dynamic load data of the building every hour throughout the year and introduces a calculation method for the comprehensive imbalance ratio of cold and hot loads to achieve a quantitative assessment of the risk of thermal imbalance, thereby providing a scientific basis for subsequent refined design and effectively overcoming the extensiveness problem caused by the reliance on peak load estimation in traditional methods.

[0009] 2. This invention constructs a three-dimensional heat transfer numerical calculation model of buried pipe groups to simulate the evolution of the temperature field of rock and soil under long-term operation conditions. Based on the temperature change trend and the accumulated net heat gain, it identifies the location of thermal imbalance and distinguishes the type of thermal imbalance, and delineates the cold accumulation zone, hot accumulation zone and thermal balance zone, laying the foundation for subsequent targeted thermal regulation.

[0010] 3. This invention differentiates the setting of heat replenishment, heat dissipation, and heat exchange units in the thermal imbalance region, and combines a multi-mode collaborative operation strategy to achieve internal circulation and efficient utilization of heat in the soil and rock mass. For various operating conditions with changing load characteristics, the system can achieve adaptive response through flexible adjustment of modes such as heat migration, heat dissipation, and heat replenishment, keeping the temperature of the soil and rock mass within a safe and efficient operating range, thus improving the system's adaptability to complex operating conditions and its long-term operational stability. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0013] Figure 2 This is a structural block diagram of the present invention.

[0014] Figure 3 This is a flowchart illustrating the layout and operation strategy of the thermal control unit of the present invention. Detailed Implementation

[0015] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a ground source heat pump buried pipe system design method based on building load variations proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0017] The following description, in conjunction with the accompanying drawings, details a specific scheme for a ground source heat pump buried pipe system design method based on building load variations provided by the present invention.

[0018] This invention aims to proactively identify and differentiate the treatment of thermal imbalance areas by simulating the impact of building dynamic loads on the temperature field of soil and rock, thereby improving the long-term operating efficiency and stability of ground source heat pump systems.

[0019] Specifically, the method first acquires hourly dynamic load data of the building throughout the year and calculates the imbalance ratio of cold and hot loads to assess the risk of thermal imbalance. Next, the dynamic load data is imported into a three-dimensional heat transfer numerical calculation model of the buried pipe network to simulate the evolution of the soil and rock temperature field during the design operating cycle. Then, based on the simulation results, the temperature change trend and accumulated net heat gain are analyzed, and the soil and rock area is divided into cold accumulation zone, hot accumulation zone, and thermal balance zone. Finally, heating, heat dissipation, and heat exchange units are set up in each zone, and a multi-mode collaborative start-up and operation strategy is formulated. This invention solves the problems of traditional designs being unable to simulate long-term thermal imbalance and having poor system adaptability, achieving accurate prediction and zoning of the soil and rock thermal field, and improving the long-term stability and robustness of the system through internal heat scheduling.

[0020] Please see Figure 1 and Figure 2 As shown, the present invention provides a design method for a ground source heat pump buried pipe system based on building load changes, including the following steps S1 to S4.

[0021] This invention relates to a design method for a ground source heat pump buried pipe system based on building load changes. The aim is to proactively identify and differentiate the treatment of thermal imbalance areas by accurately simulating the impact of building dynamic loads on the temperature field of the surrounding soil and rock mass of the buried pipe group, so as to improve the long-term operating efficiency and stability of the ground source heat pump system.

[0022] In one embodiment of the present invention, to effectively address the potential thermal imbalance problem caused by the long-term operation of a ground source heat pump system, a thorough analysis of the building load characteristics is first required. Considering that the actual energy load of a building is not constant but dynamically changes with factors such as seasons and work schedules, a long-term mismatch between these dynamically changing heating and cooling loads will lead to an imbalance between the accumulated heat absorption and release in the underground soil and rock, resulting in heat accumulation or cold accumulation, which in turn affects the heat exchange efficiency of the heat pump unit and the long-term stability of the system. Therefore, the first step is to start from the source of the building load and assess the risk of thermal imbalance.

[0023] Therefore, it is necessary to obtain hourly dynamic load data of the building throughout the year and perform multi-dimensional statistical analysis on it. By analyzing the intensity-frequency distribution of heating and cooling loads, the degree of matching between the heat absorption and release processes of the soil and rock mass can be preliminarily determined; at the same time, calculating the imbalance ratio of the total heating and cooling loads can macroscopically assess the disturbance of the system operation to the annual thermal balance of the soil and rock mass.

[0024] S1. Thermal imbalance risk assessment, specifically including the following steps: S11. Obtain the building's hourly dynamic load data throughout the year, statistically analyze the intensity-frequency distribution of cooling and heating loads and calculate the imbalance ratio of cooling and heating loads. The specific process includes: S111. Collect the building's thermal parameters and the basic data required for energy consumption simulation, and use energy consumption simulation software to construct a dynamic load simulation model that reflects the building's operating characteristics, generating an annual dynamic load spectrum curve with hourly time granularity.

[0025] S112. Perform Fourier transform on the dynamic load spectrum curve throughout the year to analyze and obtain multiple load periods and cumulative load of cold and hot loads, and obtain the peak load and duration of each load period.

[0026] S113. Based on the peak load of each load period, determine the range of peak load values ​​and divide it into several continuous load intervals.

[0027] The cumulative duration of cooling and heating load periods within each load interval is calculated and input into a preset first imbalance ratio calculation model to determine the first imbalance ratio of cooling and heating loads. The first imbalance ratio calculation model is as follows: .

[0028] in, Indicates the first unbalanced proportion. Indicates the first The numbering of each load interval, , They represent the first The cumulative duration of cooling load periods and heating load periods within each load interval. This represents a pre-defined positive constant close to zero.

[0029] S114. Calculate the ratio of the cumulative cooling load to the cumulative heating load, and take the absolute value of the difference between the ratio and 1 to obtain the second imbalance ratio of the cooling and heating loads.

[0030] S115. Sum the first imbalance ratio and the second imbalance ratio to obtain the comprehensive imbalance ratio of cooling and heating loads.

[0031] S12. Based on the imbalance ratio of cooling and heating loads, determine whether there is a risk of thermal imbalance. The specific method is to compare the overall imbalance ratio of cooling and heating loads with a preset imbalance ratio threshold. If it exceeds the threshold, it is determined that there is a risk of thermal imbalance; otherwise, it is determined that there is no risk of thermal imbalance.

[0032] S13. If there is a risk of thermal imbalance, proceed to step S2; otherwise, terminate the design process.

[0033] It should be noted that building cooling load refers to the amount of heat that needs to be removed from the interior of a building per unit time, while building heating load refers to the amount of heat that needs to be added to the building per unit time.

[0034] As an example, the method for constructing a building dynamic load simulation model is as follows: First, collect the thermal parameters of the building envelope, typical meteorological data of the location, and hourly usage schedules of different functional areas inside the building.

[0035] Then, based on the collected data, the geometric model and thermal physical model of the building are constructed using energy consumption simulation software. In the software, the thermal properties of the building envelope corresponding to each functional area are assigned, the hourly external disturbance conditions in the typical meteorological year data are set, and the internal disturbance parameters such as the occupancy rate of personnel, lighting and equipment usage rate in each functional area are set according to the hourly usage schedule.

[0036] Finally, the energy consumption simulation calculation for the set-up model is performed hourly throughout the year, and the hourly heating and cooling load of the building is output, thereby constructing a dynamic load simulation model that can reflect the actual usage characteristics of the building.

[0037] It should be noted that in the first unbalanced proportion calculation model, Indicates the first The relative proportion of the cumulative duration of heating and cooling load periods within each load interval; where, the numerator This reflects the absolute difference between cooling and heating loads within this range; the larger the value, the greater the imbalance between cooling and heating loads within this range. The denominator... This represents the total duration of the heating and cooling load periods within the specified interval. It is used to normalize the differences and thus eliminate the impact of the differences in the total duration of different intervals on the evaluation results. This is a pre-defined positive constant close to zero. Its purpose is to prevent the denominator from being zero, which would render the calculation meaningless and ensure that the formula is mathematically valid in all cases.

[0038] By analyzing all load intervals ( The first unbalanced proportion is obtained by summing the absolute values ​​of the above ratios. This value comprehensively reflects the degree of difference in the distribution of annual heating and cooling loads across different load intensity ranges: The larger the value, the more uneven the distribution of the duration of heating and cooling loads across different intensity ranges, indicating a significant misalignment in the temporal distribution of heat absorption and release processes in the soil and rock mass, thus exacerbating the risk of thermal imbalance; conversely, a smaller value indicates a more uneven distribution. The smaller the value, the closer the duration distribution of the heating and cooling loads in each interval, and the smaller the disturbance of the system operation to the temperature field of the soil and rock mass.

[0039] It should be noted that the setting basis and adjustment logic of the unbalanced ratio threshold for hot and cold loads are as follows: Setting basis: The unbalanced ratio threshold is determined by theoretical calculation based on the thermal diffusivity of the soil and rock, the heat exchange per unit well depth of the buried pipe heat exchanger, and the initial average temperature of the soil and rock, so as to ensure that the natural heat dissipation capacity of the soil and rock can neutralize the unbalanced load ratio within a complete annual operating cycle.

[0040] Adjustment logic: Based on the test results of the thermal properties of the soil and rock at the actual engineering site, the unbalance ratio threshold is dynamically corrected: when the thermal conductivity of the soil and rock is greater than the preset standard value or the groundwater flow rate is fast, the value of the unbalance ratio threshold is appropriately increased.

[0041] When the thermal conductivity of the soil and rock is less than the preset standard value or it belongs to a dense clay layer, the value of the unbalanced ratio threshold should be appropriately lowered.

[0042] In one embodiment of the present invention, the unbalance ratio threshold is set to a range of 20% to 35%. For gravel strata with good thermal conductivity, 35% is used; for clay strata with poor thermal conductivity, 20% is used; and for conventional sub-clay strata, 20% to 35% is used.

[0043] Once step S1 determines that there is a risk of thermal imbalance, it is necessary to further investigate the specific evolution of the temperature field of the soil and rock around the buried pipe group under this dynamic load, so as to provide a quantitative basis for the identification of the location of thermal imbalance and the design of the thermal control unit.

[0044] S2. Thermal response simulation: The dynamic load data obtained in step S1 is used as input conditions and imported into the pre-constructed three-dimensional heat transfer numerical calculation model of the buried pipe group. The evolution law of the temperature field of the soil and rock mass around the buried pipe group during the design operation cycle is simulated and analyzed, and a temperature change cloud map of the soil and rock mass is generated.

[0045] In a specific embodiment of the present invention, the process of constructing a three-dimensional heat transfer numerical calculation model of the buried pipe group and performing thermal response simulation includes the following steps: S211, establishing a geometric model: based on the design burial depth, borehole spacing, number of boreholes and array arrangement of the buried pipe heat exchanger, a full-size three-dimensional geometric model containing the buried pipe group and its surrounding soil and rock is constructed using numerical simulation software. The buried pipe is set as a single U-shaped, double U-shaped or sleeve-type actual physical structure, and the fluid area inside the pipe and the pipe wall entity are retained.

[0046] S212. Define physical property parameters and initial conditions: Based on the geological survey report or thermal response test report, define the thermal physical property parameters of the soil and rock mass, backfill material, buried pipe wall and circulating fluid, including but not limited to density, specific heat capacity and thermal conductivity.

[0047] The initial temperature distribution of the entire computational domain (soil and buried pipes) is set, usually by taking the initial average temperature of the soil and rock or the temperature of the constant temperature layer at the location as the initial condition.

[0048] S213. Set boundary conditions and heat load input: Set the bottom and side boundaries of the soil and rock mass as adiabatic or isothermal boundaries, and set the top boundary as a third type of boundary condition that allows for convective heat exchange with the atmosphere.

[0049] The hourly dynamic load data of the building throughout the year obtained in step S1 is used as a dynamic thermal boundary condition that varies with time, in the form of heat flux density or fluid inlet and outlet temperature, and is applied to the inner wall surface or fluid domain of the buried pipe heat exchanger.

[0050] S214. Mesh generation and solution calculation: The above geometric model is discretized using structured or unstructured meshes, and local mesh refinement is performed in areas with drastic temperature gradient changes, such as near the buried pipe wall and inside the borehole.

[0051] Based on the finite volume method or finite element method, an unsteady heat transfer control equation is established, and the time step (such as hourly or daily) and convergence accuracy are set for iterative solution.

[0052] S215. Model Verification and Output: The simulated water temperature at the outlet of the buried pipe or the heat exchange per unit length meter is compared and verified with the theoretical value or measured data under the design conditions to ensure the accuracy of the model.

[0053] The post-processing module extracts and outputs the evolution law of the temperature field of the soil and rock mass at different times and depths during the running cycle, as well as the corresponding temperature change cloud map of the soil and rock mass.

[0054] Based on the massive temperature field data generated by the simulation in step S2, the specific location and degree of thermal imbalance can be precisely identified and the region can be divided.

[0055] S3. Identification and differentiation of thermal imbalance areas, specifically including the following steps: S31. Based on the simulation results of step S2, determine the location of thermal imbalance by temperature change trend. The specific process is as follows: S311. Grid discretize the rock and soil around the buried pipe group to obtain several control units for characterizing spatial location.

[0056] S312. Based on the temperature change cloud map of the soil and rock mass during the operating cycle, extract the time series temperature data of each control unit in different years during the operating cycle, and draw the temperature change curve of each control unit over time according to the time series temperature data.

[0057] S313. Compare the temperature change curves of each control unit over time with the initial equilibrium temperature of the soil and rock mass.

[0058] If the temperature change curve over time shows a unidirectional continuous drift trend and does not tend to return to the initial equilibrium state throughout the entire operating cycle, then the control unit is determined to have experienced thermal imbalance; otherwise, the control unit is determined not to have experienced thermal imbalance.

[0059] It should be noted that a unidirectional continuous drift trend includes a unidirectional continuous upward trend and a unidirectional continuous downward trend.

[0060] S314. Statistically analyze all control units that are identified as having thermal imbalance, and perform spatial cluster analysis on them to aggregate adjacent or spatially concentrated thermal imbalance control units into several continuously distributed thermal imbalance regions.

[0061] S32. Determine whether the heat imbalance type is cold accumulation or hot accumulation based on the cumulative net heat gain. The specific process is as follows: S321. Calculate the cumulative net heat gain of each heat imbalance area during the operating cycle. The cumulative net heat gain is the difference between the total heat released by the buried pipe system to the soil and rock mass and the total heat absorbed from the soil and rock mass.

[0062] S322. Determine the type of imbalance in the corresponding thermal imbalance region based on the sign of the cumulative net heat gain.

[0063] If the cumulative net heat gain is greater than zero, the region is determined to be a thermal accumulation type of imbalance.

[0064] If the cumulative net heat gain is less than zero, the region is determined to be a cold-accumulation type imbalance.

[0065] It should be noted that the cumulative net heat gain reflects the net heat absorption state of the rock and soil mass during the operating cycle: when the cumulative net heat gain is greater than zero, it indicates that the rock and soil mass as a whole is in a net heat absorption state, and the rock and soil temperature is on the rise, that is, heat accumulation occurs, and the larger the value of the cumulative net heat gain, the more serious the degree of heat accumulation.

[0066] When the cumulative net heat gain is less than zero, it indicates that the rock and soil mass as a whole is in a state of net heat release, and the temperature of the rock and soil is decreasing, that is, cold accumulation occurs. The larger the absolute value of the cumulative net heat gain, the more severe the degree of cold accumulation.

[0067] S33. Divide the rock and soil mass into cold accumulation zone, hot accumulation zone and thermal equilibrium zone. The specific method is as follows: determine the thermal imbalance zone that is determined to be cold accumulation type as cold accumulation zone.

[0068] The thermal imbalance region that is determined to be of the thermal accumulation type is defined as the thermal accumulation zone.

[0069] The remaining area in the rock and soil mass region, excluding the cold deposition zone and the hot deposition zone, is defined as the thermal equilibrium zone.

[0070] It should be noted that the definitions, classification criteria, and physical significance of the cold accumulation zone, hot accumulation zone, and thermal equilibrium zone are detailed in Table 1.

[0071] Table 1. Detailed Explanation of Cold Accumulation Zone, Hot Accumulation Zone, and Thermal Balance Zone

[0072]

[0073] Once the specific distribution of cold accumulation zone, hot accumulation zone, and thermal equilibrium zone in the rock and soil mass is clarified, thermal control units can be designed and their operation strategies can be formulated based on the thermal characteristics of different regions.

[0074] S4. Construct an active thermal regulation architecture, see [reference]. Figure 3 As shown, a heat replenishment unit, a heat dissipation unit, and a heat exchange unit are respectively set in the cold accumulation zone, the hot accumulation zone, and the boundary area. The start-up and operation strategies of each thermal control unit are formulated. Specifically, the start-up and operation strategy of the thermal control unit is as follows: if the hot accumulation zone is too hot and the cold accumulation zone is too cold, the heat exchange unit is started and the thermal migration mode is run.

[0075] If the hot accumulation area exceeds the temperature while the cold accumulation area is normal, the heat dissipation unit will be activated and the heat dissipation mode will be run.

[0076] If the cold accumulation zone is too cold and the hot accumulation zone is normal, the heating unit will be activated and the heating mode will be run.

[0077] In a preferred embodiment of the present invention, the method for determining whether the thermal accumulation zone exceeds the temperature is: real-time monitoring of the temperature of the soil and rock mass in the thermal accumulation zone and comparing it with a preset upper limit temperature threshold.

[0078] If the temperature exceeds the upper limit threshold, the heat accumulation zone is determined to be in an over-temperature state; otherwise, it is determined to be in a normal temperature state.

[0079] In a preferred embodiment of the present invention, the method for determining whether the cold accumulation zone is too cold is: to monitor the temperature of the rock and soil in the cold accumulation zone in real time and compare it with a preset lower limit temperature threshold.

[0080] If the temperature is below the lower limit threshold, the cold accumulation zone is determined to be in a supercooled state; otherwise, it is determined to be in a normal temperature state.

[0081] In one specific embodiment of the present invention, the heat dissipation unit adopts a deep backup vertical buried pipe to enhance the heat dissipation effect of the rock and soil by utilizing the low temperature characteristics of deep geology; the heat replenishment unit adopts a shallow horizontal buried pipe or a solar coupled heat exchange pipeline to replenish heat to the rock and soil by means of surface solar energy or air heat energy; the heat exchange unit adopts an interconnected bidirectional heat exchange pipeline network, which is equipped with an intelligent reversing valve group to realize heat scheduling between the cold accumulation zone and the hot accumulation zone.

[0082] It should be noted that the temperature of the soil and rock in each area is monitored in real time through a network of temperature sensors embedded in the cold and hot accumulation zones.

[0083] It should be noted that when monitoring the temperature of the soil and rock in the cold and hot accumulation zones, this method selects the same depth layer as the buried pipe system for monitoring. The technical basis for this is that this depth layer is the area where heat exchange occurs between the buried pipe heat exchanger and the soil and rock, where the thermal imbalance phenomenon is most significant, and the monitoring data can truly reflect the actual degree of heat accumulation or cold accumulation. At the same time, it can effectively avoid the interference of the vertical temperature gradient of the soil and rock, and avoid the background temperature error introduced by inconsistent monitoring depth. In addition, this monitoring depth is consistent with the analysis area of ​​the three-dimensional heat transfer numerical calculation model in step S2 and the depth on which the area is divided in step S3, so that the real-time monitoring data and the simulation analysis results correspond to each other in the spatial dimension, providing reliable data support for the formulation of thermal control strategies.

[0084] It should be noted that the setting of the upper and lower temperature thresholds can comprehensively consider the original geothermal baseline of the soil and rock mass, the safety boundary of equipment operation, and the long-term thermal balance target, and be adjusted and optimized by combining static setting and dynamic correction. Specifically, in the design phase, the initial threshold can be preliminarily determined based on geological survey data and thermal response test data; in the system operation phase, the threshold is dynamically adjusted according to the real-time monitoring trend of soil and rock temperature changes and the evolution of thermal imbalance areas. When the thermal imbalance trend is detected to be intensifying, the threshold range can be appropriately narrowed to achieve proactive intervention, thereby keeping the soil and rock temperature within a safe and efficient operating range.

[0085] As an example, the initial average temperature of the soil and rock mass at a project site is 18℃. Based on the operating requirements of the heat pump unit and the safety boundary for freeze protection of the heat exchange medium, the upper limit temperature threshold is initially set at 30℃, and the lower limit temperature threshold is set at 2℃. During system operation, if the temperature of the soil and rock mass in the heat accumulation zone is monitored to continuously approach 28℃ and the temperature rise trend is obvious, the upper limit temperature threshold will be dynamically lowered to 28℃ to activate the heat dissipation unit in advance and prevent the temperature of the soil and rock mass from deteriorating further.

[0086] Furthermore, considering the various possible scenarios that may occur after the heat exchange unit migrates heat from the hot accumulation zone to the cold accumulation zone, to avoid frequent switching between multiple modes and potential control oscillations, the start and stop of the heat migration mode, heat dissipation mode, and heat replenishment mode in this invention all employ a hysteresis comparison control strategy. Specifically, a recovery temperature threshold (below the start threshold) is set for the over-temperature state, and a recovery temperature threshold (above the start threshold) is set for the under-cooled state. When the temperature of the soil and rock mass in the hot accumulation zone is higher than the start threshold, the heat dissipation mode is activated until the temperature drops to the recovery threshold, thus avoiding frequent start-stop cycles near the thresholds. Similarly, when the start conditions for the heat migration mode are simultaneously met, the heat migration mode is activated first. During the operation of this mode, the start conditions of other single modes are temporarily disabled or adjusted until the thermal imbalance areas are all restored to within their respective recovery thresholds, and then a new judgment is made based on real-time monitoring data.

[0087] In another specific embodiment, the thermal migration mode is prioritized to achieve internal energy circulation, and the corresponding heat replenishment mode or heat dissipation mode is activated only when a single area is unbalanced.

[0088] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0089] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0090] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0091] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0092] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0093] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0094] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a ground source heat pump buried pipe system based on building load variations, characterized in that, Includes the following steps: S1. Obtain the building's hourly dynamic load data throughout the year, statistically analyze the intensity-frequency distribution of cooling and heating loads, and calculate the imbalance ratio of cooling and heating loads. Based on this, determine whether there is a risk of thermal imbalance. If so, proceed to S2; otherwise, terminate the design process. S2. Using the dynamic load data obtained in S1 as input conditions, import the pre-constructed three-dimensional heat transfer numerical calculation model of the buried pipe group, simulate and analyze the evolution law of the temperature field of the soil and rock mass around the buried pipe group during the design operation cycle, and generate a temperature change cloud map of the soil and rock mass. S3. Based on the simulation results of S2, determine the location of thermal imbalance by the temperature change trend, and determine whether the thermal imbalance type is cold accumulation or hot accumulation by combining the cumulative net heat gain. Then, divide the rock and soil area into cold accumulation area, hot accumulation area and thermal balance area. S4. Heat replenishment units, heat dissipation units, and heat exchange units are respectively set up in the cold accumulation area, hot accumulation area, and their boundary area, and start-up and operation strategies for each thermal control unit are formulated.

2. The method according to claim 1, wherein: The method for calculating the imbalance ratio of cooling and heating loads includes: S111. Collect basic data required for building thermal parameters and energy consumption simulation, and use energy consumption simulation software to construct a dynamic load simulation model that reflects the building's operating characteristics, generating an annual dynamic load spectrum curve with hourly time granularity. S112. Perform Fourier transform on the dynamic load spectrum curve throughout the year to analyze and obtain multiple load periods and cumulative load of cold and hot loads, and obtain the peak load and duration of each load period. S113. Based on the peak load of each load period, determine the range of peak load values ​​and divide it into several consecutive load intervals; The cumulative duration of cooling load periods and heating load periods within each load interval is calculated and input into the preset first imbalance ratio calculation model to determine the first imbalance ratio of cooling and heating loads. S114. Calculate the ratio of the cumulative cooling load to the cumulative heating load, and take the absolute value of the difference between the ratio and 1 to obtain the second imbalance ratio of the cooling and heating loads. S115. Sum the first imbalance ratio and the second imbalance ratio to obtain the comprehensive imbalance ratio of cooling and heating loads.

3. The method of claim 2, wherein: The first unbalance ratio calculation model is as follows: ； wherein, represents a first unbalance ratio, represents a number of a first load interval, represents a number of a first load interval, , respectively represent cumulative durations of cold load periods and hot load periods in the first load interval, represents a preset positive constant close to zero.

4. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 1, characterized in that: The method for determining whether there is a risk of thermal imbalance is as follows: The combined imbalance ratio of heating and cooling loads is compared with a preset imbalance ratio threshold. If the ratio exceeds the threshold, it is determined that there is a risk of thermal imbalance; otherwise, it is determined that there is no risk of thermal imbalance.

5. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 1, characterized in that: The method for determining the location of thermal imbalance is as follows: S311. The soil and rock mass around the buried pipe group is discretized into a grid to divide it into several control units for characterizing spatial location. S312. Based on the temperature change cloud map of the soil and rock mass during the operation cycle, extract the time series temperature data of each control unit in different years during the operation cycle, and draw the temperature change curve of each control unit over time according to the time series temperature data. S313. Compare the temperature change curves of each control unit over time with the initial equilibrium temperature of the soil and rock mass: If the temperature change curve over time shows a unidirectional continuous drift trend and there is no tendency to return to the initial equilibrium state during the entire operating cycle, it is determined that the control unit has experienced thermal imbalance; otherwise, it is determined that the control unit has not experienced thermal imbalance. S314. Statistically analyze all control units that are identified as having thermal imbalance, and perform spatial cluster analysis on them to aggregate adjacent or spatially concentrated thermal imbalance control units into several continuously distributed thermal imbalance regions.

6. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 5, characterized in that: The method for determining the type of thermal imbalance is as follows: S321. Calculate the cumulative net heat gain of each thermal imbalance zone during the operating cycle. The cumulative net heat gain is the difference between the total heat released by the buried pipe system to the soil and rock mass and the total heat absorbed from the soil and rock mass. S322. Determine the type of imbalance in the corresponding thermal imbalance region based on the sign of the cumulative net heat gain: If the cumulative net heat gain is greater than zero, the region is determined to be a thermal accumulation type of imbalance. If the cumulative net heat gain is less than zero, the region is determined to be a cold-accumulation type imbalance.

7. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 6, characterized in that: The method for dividing the soil and rock mass into regions is as follows: The thermal imbalance area identified as a cold accumulation type imbalance is designated as the cold accumulation zone. The thermal imbalance area that is determined to be of the thermal accumulation type is defined as the thermal accumulation zone; The remaining area in the rock and soil mass region, excluding the cold deposition zone and the hot deposition zone, is defined as the thermal equilibrium zone.

8. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 1, characterized in that: The specific startup and operation strategy of the thermal control unit is as follows: If the hot accumulation zone is too hot and the cold accumulation zone is too cold, the heat exchange unit will be activated and the thermal migration mode will be run. If the hot accumulation area exceeds the temperature while the cold accumulation area is normal, the heat dissipation unit will be activated and the heat dissipation mode will be run. If the cold accumulation zone is too cold and the hot accumulation zone is normal, the heating unit will be activated and the heating mode will be run.

9. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 8, characterized in that: The method for determining whether the thermal accumulation zone exceeds the temperature is as follows: Real-time monitoring of the temperature of the soil and rock mass in the thermal accumulation zone and comparison with the preset upper limit temperature threshold; If the temperature exceeds the upper limit threshold, the heat accumulation zone is determined to be in an over-temperature state; otherwise, it is determined to be in a normal temperature state.

10. The design method for a ground source heat pump buried pipe system based on building load variation according to claim 8, characterized in that: The method for determining whether the cold accumulation zone is overcooled is as follows: Real-time monitoring of the temperature of the soil and rock mass in the cold accumulation zone and comparison with the preset lower temperature threshold. If the temperature is below the lower limit threshold, the cold accumulation zone is determined to be in a supercooled state; otherwise, it is determined to be in a normal temperature state.

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