A high-efficiency heat energy collection and conversion system for carbon dioxide in a middle-deep ground source

Abstract

The application provides a middle-deep layer ground source carbon dioxide high-efficiency heat energy collection and conversion system, which comprises a geothermal well and a ground energy hub module, the geothermal well comprises an inner flow channel and an outer flow channel; the ground energy hub module comprises a compressor set, a user-side heat exchanger, a flow path control valve set and a throttling assembly, the flow path control valve set is provided with multiple interfaces, and the geothermal well, the compressor set, the user-side heat exchanger and the throttling assembly are communicated with corresponding interfaces, wherein the flow path control valve set switches the internal flow channel, so that the multiple interfaces are conducted in a first mode to form a heating mode, or the multiple interfaces are conducted in a second mode to form a refrigeration mode. The middle-deep layer ground source carbon dioxide high-efficiency heat energy collection and conversion system of the embodiment of the application realizes the all-year utilization of geothermal resources and improves the utilization rate of the geothermal well.

Description

Technical Field

[0001] This invention relates to the field of geothermal system technology, and in particular to a high-efficiency geothermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide. Background Technology

[0002] In existing technologies, medium-deep geothermal systems are mostly used for winter heating, and their operation mode is relatively simple. In this mode, geothermal wells act as heat sources, extracting underground heat through circulating working fluid and supplying heat to the user side. However, during the summer cooling season, due to the lack of an effective mechanism for using geothermal wells as cold sources, they are usually idle and cannot participate in the cooling process. This seasonal limitation results in the underutilization of geothermal resources throughout the year, reducing the overall energy efficiency and economic value of individual wells. Summary of the Invention

[0003] This invention provides a high-efficiency geothermal energy harvesting and conversion system for medium-deep geothermal carbon dioxide, which solves the problem of low utilization efficiency of geothermal wells in the prior art and improves the utilization rate of geothermal wells.

[0004] This invention provides a high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide, comprising: Geothermal wells include external and internal flow channels; The ground energy hub module includes a compressor unit, a user-side heat exchanger, a flow path control valve group, and a throttling component. The flow path control valve group is provided with multiple interfaces, and the geothermal well, the compressor unit, the user-side heat exchanger, and the throttling component are connected to the corresponding interfaces. The flow path control valve group switches the internal flow channels to enable multiple interfaces to be connected in a first manner to form a heating mode, or enables multiple interfaces to be connected in a second manner to form a cooling mode.

[0005] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system includes: An integrated power generation and regeneration module is provided. In the heating mode, the input end of the integrated power generation and regeneration module is connected to the user-side heat exchanger, and the output end of the integrated power generation and regeneration module is connected to the flow path control valve group. The integrated power generation and heat recovery module is used to expand and generate electricity and recover waste heat from at least a portion of the heat exchange medium from the user-side heat exchanger.

[0006] In some embodiments, the integrated power generation and regeneration module includes: A regenerator, the input end of which is connected to the user-side heat exchanger, and the output end of which is connected to the flow path control valve group; A bypass valve, the input and output of which are both connected to the regenerator; An expansion generator, wherein both the input and output ends of the expansion generator are connected to the regenerator, and the bypass valve and the expansion generator are connected in parallel; A three-way valve is connected to the regenerator, the bypass valve, and the expansion generator.

[0007] In some embodiments, the integrated power generation and regeneration module includes a heating mode and a power generation mode. In the heating mode, the regenerator is connected to the bypass valve through the three-way valve. In the power generation mode, the regenerator is connected to the expansion generator through the three-way valve.

[0008] In some embodiments, the geothermal well has an inner pipe and an outer pipe arranged coaxially inside, the inner pipe forming the inner flow channel, and the outer peripheral wall of the inner pipe and the inner peripheral wall of the outer pipe forming the outer flow channel.

[0009] In some embodiments, the plurality of interfaces include: Port K1 is connected to the output terminal of the compressor unit; Port K2 is connected to the input terminal of the compressor unit; Port K3 is connected to the input terminal of the user-side heat exchanger; Port K4 is connected to the output end of the user-side heat exchanger; K5 port is connected to the internal flow channel; Port K6 is connected to the external flow channel; Port K7 is connected to the output terminal of the throttling component; Port K8 is connected to the input terminal of the throttling component; In the first method, port K1 is connected to port K3, port K2 is connected to port K5, and port K6 is connected to port K7; In the second method, port K1 is connected to port K5, port K2 is connected to port K4, port K3 is connected to port K7, and port K6 is connected to port K8.

[0010] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system includes: An auxiliary air source heat exchanger is connected to the input end of the throttling component and the K8 port to cool the heat exchange medium.

[0011] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system includes: The control system is electrically connected to the ground energy hub module and the integrated power generation and recuperation module, and is also electrically connected to the power grid dispatching system.

[0012] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system includes: A switching valve is located between the input end of the integrated power generation and regeneration module and the output end of the user-side heat exchanger; In the heating mode, the switch valve is open; in the cooling mode, the switch valve is closed.

[0013] In some embodiments, the outer peripheral walls of both the inner tube and the outer tube are provided with fins.

[0014] The medium-deep geothermal carbon dioxide high-efficiency thermal energy harvesting and conversion system of this invention, through the setting of a multi-interface flow path control valve group, directly connects the geothermal well to a unified circulation loop consisting of a compressor unit, a user-side heat exchanger, and a throttling component. This allows the same geothermal well and the same set of equipment to be used as a heat source for heating in winter and as a cold source for cooling in summer. This structure avoids the idleness of geothermal wells during the non-heating season, realizes year-round utilization of geothermal resources, and improves the utilization rate of geothermal wells. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide provided by the present invention.

[0017] Figure 2 This is a schematic diagram of the geothermal well structure of the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system provided by the present invention.

[0018] Figure 3 This is a schematic diagram of the control logic of the high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide provided by the present invention.

[0019] Figure label: 100. High-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide; 1. Geothermal well; 21. Outer pipe; 22. Inner pipe; 3. Ground energy hub module; 31. Flow control valve group; 32. Compressor unit; 33. User-side heat exchanger; 34. Throttling component; 4. Integrated power generation and regeneration module; 41. Regenerator; 42. Expansion generator; 43. Bypass valve; 44. Three-way valve; 5. Auxiliary air source heat exchanger; 6. Switch valve. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] like Figures 1 to 3 As shown, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention includes a geothermal well 1 and a ground energy hub module 3.

[0022] The geothermal well 1 includes an internal flow channel and an external flow channel. The ground energy hub module 3 includes a compressor unit 32, a user-side heat exchanger 33, a flow path control valve group 31, and a throttling component 34. The flow path control valve group 31 is provided with multiple interfaces, and the geothermal well 1, the compressor unit 32, the user-side heat exchanger 33, and the throttling component 34 are connected to the corresponding interfaces.

[0023] The flow path control valve group 31 switches the internal flow path to enable multiple interfaces to be connected in a first manner to form a heating mode, or enables multiple interfaces to be connected in a second manner to form a cooling mode.

[0024] In heating mode, the heat exchange medium transfers heat from geothermal well 1 to users to achieve heating. In cooling mode, the heat exchange medium transfers cold energy from geothermal well 1 to users to achieve cooling.

[0025] The heat exchange medium is carbon dioxide.

[0026] The flow path control valve assembly 31 has multiple interfaces. The geothermal well 1, compressor unit 32, user-side heat exchanger 33, and throttling component 34 are connected to their respective interfaces, forming a closed heat exchange working fluid circulation loop. The flow path control valve assembly 31 has a switchable flow channel structure inside, which can change the flow channel connection relationship to make each interface conduct in a preset manner, thereby supporting the system to operate in different modes in different seasons.

[0027] In heating mode, the flow path control valve group 31 switches to the first conduction mode. The heat exchange working fluid flows out from the throttling component 34, in a low-temperature, low-pressure gas-liquid two-phase state. Guided by the flow path control valve group 31, the working fluid enters the outer channel of the geothermal well 1, absorbs heat from the rock strata inside the well, and gradually evaporates completely into a medium-temperature, medium-pressure gas. The evaporated gaseous working fluid returns to the ground from the inner channel of the geothermal well 1, and enters the suction port of the compressor unit 32 through the flow path control valve group 31; it is compressed in the compressor unit 32, becoming a high-temperature, high-pressure supercritical fluid. Then, the high-temperature, high-pressure working fluid enters the user-side heat exchanger through the flow path control valve group 31, where it releases heat to the building-side circulating water. The working fluid is cooled and condensed into a high-pressure liquid. The high-pressure liquid working fluid flows out from the user-side heat exchanger 33, enters the throttling component 34 through the flow path control valve group 31, and after throttling, returns to a low-temperature, low-pressure gas-liquid two-phase state, re-enters the geothermal well 1, and begins the next cycle.

[0028] In cooling mode, the flow path control valve group 31 switches to the second conduction mode. The heat exchange working fluid, after being compressed by the compressor unit 32, becomes a high-temperature, high-pressure supercritical fluid. Guided by the flow path control valve group 31, the working fluid first enters the inner channel of the geothermal well 1, where it releases heat to the cooler rock strata and gradually condenses into a high-pressure liquid. The condensed liquid working fluid returns to the surface from the outer channel of the geothermal well 1, and enters the throttling component 34 through the flow path control valve group 31, where it becomes a low-temperature, low-pressure gas-liquid two-phase state after throttling. The low-temperature, low-pressure working fluid enters the user-side heat exchanger 33 through the flow path control valve group 31, where it absorbs heat from the building-side circulating water to achieve cooling, and evaporates into a low-temperature, low-pressure gas. The evaporated gaseous working fluid flows out from the user-side heat exchanger 33, returns to the suction port of the compressor unit 32 through the flow path control valve group 31, is recompressed, and completes the cycle.

[0029] In existing technologies, medium-deep geothermal systems are mostly used for winter heating, and their operation mode is relatively simple. In this mode, geothermal well 1 acts as a heat source, extracting underground heat through circulating working fluid and supplying heat to the user side. However, during the summer cooling season, due to the lack of an effective mechanism for using geothermal well 1 as a cold source, it is usually idle and cannot participate in the cooling process. This seasonal functional limitation results in the underutilization of geothermal resources throughout the year, reducing the overall energy efficiency and economic value of a single well.

[0030] The medium-deep geothermal carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention, by setting up a multi-interface flow path control valve group 31, directly connects the geothermal well 1 to a unified circulation loop composed of a compressor unit 32, a user-side heat exchanger 33, and a throttling component 34, enabling the same geothermal well 1 and the same set of equipment to be used as a heat source for heating in winter and as a cold source for cooling in summer. This structure avoids the geothermal well 1 being idle during the non-heating season, realizes the year-round utilization of geothermal resources, and improves the utilization rate of the geothermal well 1.

[0031] In some embodiments, the medium-deep ground source carbon dioxide high-efficiency thermal energy collection and conversion system 100 includes an integrated power generation and regeneration module 4. In the heating mode, the input end of the integrated power generation and regeneration module 4 is connected to the user-side heat exchanger 33, and the output end of the integrated power generation and regeneration module 4 is connected to the flow path control valve group 31.

[0032] The integrated power generation and heat recovery module 4 is used to expand and generate electricity and recover waste heat from at least a portion of the heat exchange medium from the user-side heat exchanger 33.

[0033] In this embodiment, when the system is operating in heating mode, the high-pressure heat exchange medium flowing out of the user-side heat exchanger 33 no longer directly enters the throttling component 34, but instead first connects to the integrated power generation and regeneration module 4. After receiving the high-temperature and high-pressure medium, the integrated power generation and regeneration module 4 uses its pressure energy to drive expansion and generate electricity. At the same time, it absorbs the waste heat of the medium through its internal heat exchange structure, realizing the cascade utilization of energy. After completing the work or heat recovery, the medium is sent back to the flow path control valve group 31 through the output end, and then enters the throttling component 34.

[0034] The medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention, while retaining basic heating functions, adds a path for the reuse of high-pressure working fluid energy. By setting an integrated power generation and regeneration module 4 between the user-side heat exchanger 33 and the throttling component 34, the system can simultaneously achieve power generation and waste heat recovery during the heating process, avoiding energy waste caused by direct throttling of the high-pressure working fluid and improving overall energy utilization efficiency.

[0035] In some embodiments, the integrated power generation and regeneration module 4 includes a regenerator 41, a bypass valve 43, an expansion generator 42, and a three-way valve 44.

[0036] The input end of the regenerator 41 is connected to the user-side heat exchanger 33, and the output end of the regenerator 41 is connected to the flow path control valve group 31. Both the input and output ends of the bypass valve 43 are connected to the regenerator 41. Both the input and output ends of the expander generator 42 are connected to the regenerator 41, and the bypass valve 43 and the expander generator 42 are connected in parallel. The three-way valve 44 is connected to the regenerator 41, the bypass valve 43, and the expander generator 42.

[0037] In this embodiment, the integrated power generation and regeneration module 4 employs a parallel branch design: one branch is an expansion generator 42, used to expand the high-pressure working fluid to generate electricity; the other branch is a bypass valve 43, used to bypass the expansion process and directly conduct the working fluid. The regenerator 41 is connected in series in the main flow path. Its high-pressure side receives the working fluid from the user-side heat exchanger 33, while its low-pressure side receives the low-temperature working fluid returned from the expansion generator 42 or the bypass valve 43, achieving heat exchange between the high and low-pressure working fluids. A three-way valve 44 is used to control the distribution of the working fluid between the two parallel branches.

[0038] The medium-deep ground-source carbon dioxide high-efficiency thermal energy collection and conversion system 100 of this invention, by setting up a parallel expansion generator 42 and a bypass valve 43, and cooperating with a three-way valve 44 for flow distribution, enables the system to flexibly choose whether to perform expansion power generation according to operational needs.

[0039] In some embodiments, the integrated power generation and regeneration module 4 includes a heating mode and a power generation mode. In the heating mode, the regenerator 41 is connected to the bypass valve 43 via a three-way valve 44. In the power generation mode, the regenerator 41 is connected to the expansion generator 42 via the three-way valve 44.

[0040] In this embodiment, the integrated power generation and regeneration module 4 has two operating modes. In the heating mode, the three-way valve 44 guides the working fluid to the bypass valve 43 branch, bypassing the expansion generator 42, so that the waste heat of the high-pressure working fluid can be used to supply heat to users.

[0041] In power generation mode, the three-way valve 44 switches the flow direction, allowing the working fluid to flow through the expander generator 42 to expand and do work, converting it into electrical energy output. At this time, the enthalpy of the working fluid decreases, and the corresponding heating temperature drops slightly. Alternatively, in power generation mode, the three-way valve 44 guides most of the working fluid to the expander generator 42 to do work, and guides a small portion of the working fluid to the bypass valve 43 branch.

[0042] The medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention integrates a power generation and regeneration module 4, which can switch between heating and power generation. Users can choose to prioritize ensuring heating temperature or prioritizing obtaining electricity based on actual needs or external conditions (such as electricity prices), enhancing the system's adaptability to different application scenarios.

[0043] In some embodiments, the geothermal well 1 has an inner pipe 22 and an outer pipe 21 arranged coaxially inside. The inner pipe 22 forms an inner flow channel, and the outer peripheral wall of the inner pipe 22 and the inner peripheral wall of the outer pipe 21 form an outer flow channel.

[0044] In this embodiment, the geothermal well 1 employs a coaxial casing structure, with the inner pipe 22 serving as the central channel to form the inner flow channel; the annular gap between the inner pipe 22 and the outer pipe 21 forms the outer flow channel. The working fluid is diverted from the outer flow channel to the inner flow channel via a connecting pipe at the bottom of the well, forming a continuous circulation.

[0045] In some embodiments, the plurality of interfaces include ports K1, K2, K3, K4, K5, K6, K7, and K8. Port K1 is connected to the output of compressor unit 32. Port K2 is connected to the input of compressor unit 32. Port K3 is connected to the input of user-side heat exchanger 33. Port K4 is connected to the output of user-side heat exchanger 33. Port K5 is connected to the inner flow channel. Port K6 is connected to the outer flow channel. Port K7 is connected to the output of throttling component 34. Port K8 is connected to the input of throttling component 34.

[0046] In the first method, port K1 is connected to port K3, port K2 is connected to port K5, and port K6 is connected to port K7.

[0047] In the second method, port K1 is connected to port K5, port K2 is connected to port K4, port K3 is connected to port K7, and port K6 is connected to port K8.

[0048] In this embodiment, the flow path control valve group 31 is provided with eight standardized interfaces, which correspond to the inlet and outlet of each key component of the system.

[0049] The medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention enables the flow path control valve group 31 to reliably switch between two modes in a defined flow channel combination through a well-defined interface connection logic.

[0050] Optionally, the flow path control valve group 31 includes multiple two-position two-way, two-position three-way, or three-position four-way solenoid valves. By controlling the opening and closing combinations of these valves using the control system, the flow path logic of the first mode or the second mode can be realized.

[0051] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 includes an auxiliary air source heat exchanger 5.

[0052] The auxiliary air source heat exchanger 5 is connected to the input end of the throttling component 34 and the K8 port for cooling the heat exchange medium.

[0053] The auxiliary air source heat exchanger 5 is configured to start when the temperature is higher than a first preset value, or when the temperature is lower than a second preset value.

[0054] In this embodiment, the auxiliary air source heat exchanger 5 is connected to the main circuit in parallel, with one end connected to the input terminal of the throttling component 34 and the other end connected to port K8.

[0055] When the ambient temperature is too high (such as extreme high temperatures in summer), the underground condensation effect is poor, and the auxiliary air source heat exchanger 5 acts as a backcooler for the geothermal well 1. For example, the medium-deep ground source carbon dioxide high-efficiency thermal energy collection and conversion system 100 can start the auxiliary air source heat exchanger 5 when the ambient temperature is relatively low at night or in the early morning. At this time, the condensed working fluid returning from the geothermal well 1 flows through the auxiliary air source heat exchanger 5 before entering the throttling component 34. The low-temperature air is used to cool the working fluid, thereby improving the cooling capacity of the working fluid.

[0056] When the ambient temperature is too low (such as in severe winter), the auxiliary air source heat exchanger 5 acts as a precooler for the geothermal well 1. For example, cold air is used to cool part or all of the working fluid flowing out of the integrated power generation and regeneration module 4 and about to enter the throttling component 34, reducing the temperature of the working fluid to a level lower than originally designed. This cooler working fluid then enters the geothermal well 1, thereby increasing the temperature difference between the working fluid and the geothermal rock layer and improving the instantaneous heat extraction capacity of the working fluid.

[0057] The medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention introduces an auxiliary air source heat exchanger 5 on the basis of the main cycle, which can compensate for the insufficient underground heat exchange capacity under extreme weather conditions. This structure expands the system's applicability under extreme climatic conditions, while not changing the basic architecture of the main loop.

[0058] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 includes a control system, which is electrically connected to the ground energy hub module 3 and the integrated power generation and recuperation module 4, and is also electrically connected to the power grid dispatching system.

[0059] The control system is configured to receive peak shaving or demand-side response commands from the power grid dispatching system and adjust the integrated power generation and regeneration module 4 to switch between heating mode and power generation mode.

[0060] During peak electricity demand periods, the generator can activate its power generation mode or increase its power generation capacity to feed electricity back into the grid in order to participate in peak shaving.

[0061] During off-peak hours, switch to heating mode or reduce power generation.

[0062] In this embodiment, the control system has a communication interface with the external power grid, enabling it to receive peak-shaving commands or time-of-use pricing signals issued by the power grid in real time. Based on this information, the control system automatically adjusts the operating state of the integrated power generation and regeneration module 4: during peak grid load periods, it prioritizes the activation of the expansion generator 42 branch to increase power generation output and feed power to the grid; during off-peak load periods, it reduces power generation and uses more energy to ensure heating.

[0063] The medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention can automatically adjust its own operating status according to the dispatch instructions issued by the power grid—for example, generating more electricity and supplying less heat when needed, or prioritizing heat supply during off-peak electricity demand. Therefore, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 can actively cooperate with the operation of the power grid, providing power support while supplying energy.

[0064] In some embodiments, the medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 includes a switching valve 6, which is located between the input end of the integrated power generation and regeneration module 4 and the output end of the user-side heat exchanger 33.

[0065] In heating mode, valve 6 is open. In cooling mode, valve 6 is closed.

[0066] In this embodiment, the switching valve 6 serves as the start / stop switch for the integrated power generation and regeneration module 4, and is installed on the pipeline between the outlet of the user-side heat exchanger 33 and the inlet of the module. When the medium-deep ground source carbon dioxide high-efficiency thermal energy collection and conversion system 100 switches to heating mode, the switching valve 6 opens, allowing the working fluid to flow into the integrated power generation and regeneration module 4; when the medium-deep ground source carbon dioxide high-efficiency thermal energy collection and conversion system 100 switches to cooling mode, the switching valve 6 closes, cutting off the connection between the integrated power generation and regeneration module 4 and the main circuit, avoiding unnecessary flow resistance and heat loss.

[0067] The medium-deep ground-source carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention, by setting a dedicated switching valve 6, ensures that the integrated power generation and regeneration module 4 is connected to the circulation loop only when needed. This design simplifies the process in cooling mode, reduces pump power consumption, and prevents the module from becoming a heat leakage path when not in operation.

[0068] In some embodiments, the outer peripheral walls of both the inner tube 22 and the outer tube 21 are provided with fins.

[0069] In this embodiment, both the outer walls of the inner tube 22 and the outer tube 21 of the coaxial sleeve are machined with finned structures. These fins are distributed along the length of the tube, which can increase the heat exchange area of ​​the inner tube 22 and the outer tube 21.

[0070] The medium-deep geothermal carbon dioxide high-efficiency thermal energy harvesting and conversion system 100 of this invention improves the heat exchange capacity per unit length of the well by adding fins to the surfaces of the inner pipe 22 and the outer pipe 21. This structure enhances the heat extraction or heat dissipation performance of the geothermal well 1 without increasing the well depth or pipe diameter.

[0071] Optionally, the bottom of the outer pipe 21 is provided with a U-shaped pipe in order to seal the bottom of the outer pipe 21 so that the medium turns back after touching the bottom.

[0072] In other embodiments, the control system 0 includes an energy efficiency optimization system, which includes a data receiving module and an adjustment module.

[0073] The data receiving module is used to receive real-time electricity prices, building load demand, weather forecasts, and temperature and pressure data from geothermal well 1.

[0074] The adjustment module sends adjustment commands to the execution module of the control system based on the data received by the data receiving module, so as to adjust the operating parameters of the ground energy hub module 3 and the integrated power generation and recuperation module 4, adjust and switch to heating mode or cooling mode, and adjust the integrated power generation and recuperation module 4 to switch between heating mode and power generation mode.

[0075] Temperature and pressure sensors are installed in geothermal well 1, ground energy hub module 3, integrated power generation and regeneration module 4, and other key locations.

[0076] In this embodiment, the energy efficiency optimization system acts as the upper-level decision-making unit, continuously collecting multi-source information, including real-time electricity prices, building cooling / heating load demand, weather forecasts, and temperature and pressure data from geothermal well 1.

[0077] Based on this data, the adjustment module uses preset strategies or algorithms to generate operating instructions, which are then sent to the execution module to achieve operations such as mode switching, equipment motor speed regulation, and valve opening adjustment of the medium-deep ground source carbon dioxide high-efficiency thermal energy collection and conversion system 100.

[0078] Optionally, the energy efficiency optimization system also includes a downhole thermal field management and prediction module. This module constructs and updates a dynamic model of downhole rock formation thermal recovery based on historical operating data and real-time downhole temperature sensor data. At the end of the cooling season, based on the model prediction results, it automatically decides and executes downhole thermal compensation operation. By appropriately increasing the heat discharged to the ground, it optimizes the initial temperature field around the wellbore of geothermal well 1 at the beginning of the subsequent heating season, thereby improving long-term operating energy efficiency and sustainability.

[0079] Optionally, compressor unit 32 is a semi-hermetic screw compressor designed for carbon dioxide working fluid.

[0080] In some embodiments, the energy efficiency optimization system is an artificial intelligence energy efficiency optimization system. The medium-deep ground source carbon dioxide high-efficiency thermal energy acquisition and conversion system 100 of this embodiment constructs a complete data sensing network.

[0081] In the above embodiments, the switching and optimization of all physical processes are uniformly commanded by the artificial intelligence energy efficiency optimization system, which is a continuously operating closed-loop control system. This system constructs a complete data sensing network, including interfaces for external environment and market data, monitoring of internal system operating status, and intelligent decision-making and optimization layers at multiple time scales.

[0082] I. External environment and market data interfaces include: Meteorological data interface: Real-time acquisition of weather forecasts for the next 72 hours, including ambient temperature, humidity, solar radiation intensity, etc., to provide a basis for the start and stop of the auxiliary air source heat exchanger 5.

[0083] Electricity market data interface: Receives time-of-use electricity price signals and demand-side response instructions from the power grid dispatch center, providing data support for heating modes.

[0084] User load data interface: Build a building energy management system and obtain the building's heat / cooling load demand from the building energy management system as the basic parameters for system operation.

[0085] II. Internal system operation status monitoring includes: Status monitoring: Temperature sensors are arranged in the geothermal well 1, the ground energy hub module 3, and the integrated power generation and regeneration module 4 to form a temperature sensor group. For example, temperature sensors are arranged at key nodes such as the intake and exhaust ports of the compressor unit 32, the working fluid inlet and outlet of the user-side heat exchanger 33, the inlet of the inner pipe 22 and the outer pipe 21, the pipe connected to the throttling component 34, and both sides of the regenerator 41 to monitor the working fluid temperature status in real time.

[0086] Pressure sensors are arranged in geothermal well 1, surface energy hub module 3, and integrated power generation and recuperation module 4 to form a pressure sensor group, which monitors the working fluid pressure status in real time. Temperature measuring devices are arranged along the depth direction of geothermal well 1 to construct a downhole temperature profile map, providing data for thermal field management.

[0087] Equipment status monitoring: Collect operating parameters such as the speed and power of compressor unit 32, the power generation of expansion generator 42, the opening degree of each valve, and the speed of auxiliary air source heat exchanger 5 fan.

[0088] Downhole thermal field monitoring: Temperature measuring devices are arranged along the depth direction of geothermal well 1 to construct a downhole temperature profile map and provide data for thermal field management.

[0089] III. The multi-timescale intelligent decision-making and optimization layer includes: Long-term strategic decision-making (on a seasonal / monthly basis), downhole thermal field management and resource sustainability optimization.

[0090] An embedded downhole dynamic model for rock formation thermal recovery simulates and predicts the evolution trend of the rock mass temperature field under different heat extraction / discharge powers. This downhole dynamic model can be constructed based on the basic principles of heat transfer, and uses historical operating data and real-time downhole temperature sensor data for parameter identification and model calibration. The model can be a lumped parameter model or a distributed parameter model, and its core is to describe the dynamic response process of the rock mass temperature around the wellbore as the system's heat extraction and dissipation behavior and the rock mass's own heat conduction.

[0091] The following section introduces several control decisions of an artificial intelligence energy efficiency optimization system.

[0092] Decision 1: At the end of the heating season, assess the extent of "cold buildup" caused by winter heating.

[0093] During the cooling season, based on model predictions, the system proactively performs downhole heat compensation: when predictions indicate insufficient recovery of rock mass temperature, the system will decide to moderately activate the cooling mode during periods when cooling is not required, or increase the operating time of the auxiliary air source heat exchanger 5, strategically injecting more heat into the underground to optimize the initial temperature field for the next heating season.

[0094] Mid-term mode decision-making (in days / hours), multi-energy flow optimization and grid interaction; The Model Predictive Control (MPC) optimization algorithm is adopted, with the goal of minimizing system operating costs or maximizing overall benefits. The objective function for minimizing system operating costs or maximizing overall benefits can be specifically expressed as: minimizing (grid electricity purchase cost - power generation and sales revenue) or maximizing (heating / cooling revenue + power generation and sales revenue - equipment loss costs). Decision variables in the optimization process include switching operating modes, allocating power generation / heating capacity, and starting and stopping the auxiliary air source heat exchanger 5.

[0095] Decision 2: Optimization of Cogeneration: During the heating season, the operating mode is dynamically switched according to the real-time electricity price: during peak electricity price periods, the command system switches to "power generation mode" to maximize power generation output through the expansion generator 42; during off-peak periods, it switches to "heating mode" to maximize heating efficiency by adjusting the bypass valve 43.

[0096] Participate in grid demand-side response: Upon receiving a grid peak-shaving instruction, immediately maximize power generation output to support the grid.

[0097] Short-term real-time optimization (in seconds / minutes) and precise device-level control are achieved. A strategy combining adaptive PID control and fuzzy logic control is employed. Fuzzy logic control dynamically tunes the proportional, integral, and derivative parameters of the PID controller based on system load, ambient temperature, and other operating conditions, or directly outputs control commands, overcoming the poor adjustment quality of traditional PID controllers in nonlinear, high-lag systems. For example, the speed control of compressor unit 32 is not only based on suction superheat but also incorporates its changing trend through fuzzy rules, achieving smoother and more precise regulation.

[0098] Decision 3: Pipeline Control The variable frequency speed of compressor unit 32 is dynamically adjusted according to the intake superheat.

[0099] The throttling component 34 is controlled, for example, the throttling component 34 is an electronic expansion valve, which can precisely adjust the opening of its inlet and outlet according to the superheat of the outlet of the geothermal well 1.

[0100] The power generation / bypass branch is controlled, for example, the bypass valve 43 is continuously adjusted according to the optimal power generation / heat supply ratio.

[0101] Intelligent switching of hybrid modes: For example, when the ambient temperature drops suddenly, the system benefits of activating the auxiliary air source heat exchanger 5 are automatically determined and the switching is executed.

[0102] Furthermore, the AI-powered energy efficiency optimization system must strictly adhere to the system's safe operation constraints in all timescale decisions. These constraints include, but are not limited to: the upper limits of the exhaust temperature and pressure of compressor unit 32, the maximum / minimum allowable temperature of the working fluid at each node, grid connection power limits, and equipment start-up and shutdown frequency limits. The optimization algorithm will find the optimal operating point while satisfying all these hard constraints, ensuring safe and long-term system operation while maximizing energy efficiency.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide, characterized in that, include: Geothermal well (1), including external flow channel and internal flow channel; The ground energy hub module (3) includes a compressor unit (32), a user-side heat exchanger (33), a flow path control valve group (31), and a throttling component (34). The flow path control valve group (31) is provided with multiple interfaces, and the geothermal well (1), the compressor unit (32), the user-side heat exchanger (33), and the throttling component (34) are connected to the corresponding interfaces. The flow path control valve group (31) switches the internal flow path to make multiple interfaces open in a first manner to form a heating mode, or to make multiple interfaces open in a second manner to form a cooling mode. The geothermal well (1) is provided with an inner pipe (22) and an outer pipe (21) arranged coaxially inside. The inner pipe (22) forms the inner flow channel, and the outer peripheral wall of the inner pipe (22) and the inner peripheral wall of the outer pipe (21) form the outer flow channel. The plurality of said interfaces include: Port K1 is connected to the output end of the compressor unit (32); Port K2 is connected to the input terminal of the compressor unit (32); Port K3 is connected to the input terminal of the user-side heat exchanger (33); Port K4 is connected to the output end of the user-side heat exchanger (33); Port K5 is connected to the internal flow channel; Port K6 is connected to the external flow channel; Port K7 is connected to the output terminal of the throttling component (34); Port K8 is connected to the input terminal of the throttling component (34); In the first method, port K1 is connected to port K3, port K2 is connected to port K5, and port K6 is connected to port K7; In the second method, port K1 is connected to port K5, port K2 is connected to port K4, port K3 is connected to port K7, and port K6 is connected to port K8.

2. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 1, characterized in that, The medium-deep ground-source high-efficiency carbon dioxide thermal energy harvesting and conversion system includes: In the heating mode, the input end of the integrated power generation and regeneration module (4) is connected to the user-side heat exchanger (33), and the output end of the integrated power generation and regeneration module (4) is connected to the flow path control valve group (31). The integrated power generation and heat recovery module (4) is used to expand and generate electricity and recover waste heat from at least a portion of the heat exchange medium from the user-side heat exchanger (33).

3. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 2, characterized in that, The integrated power generation and regeneration module (4) includes: The heat exchanger (41) has an input end connected to the user-side heat exchanger (33) and an output end connected to the flow path control valve group (31). A bypass valve (43) is provided, the input and output of which are connected to the regenerator (41). An expansion generator (42) is provided, the input and output ends of which are connected to the regenerator (41), and the bypass valve (43) and the expansion generator (42) are connected in parallel. A three-way valve (44) is connected to the regenerator (41), the bypass valve (43), and the expansion generator (42).

4. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 3, characterized in that, The integrated power generation and regeneration module (4) includes a heating mode and a power generation mode. In the heating mode, the regenerator (41) is connected to the bypass valve (43) through the three-way valve (44). In the power generation mode, the regenerator (41) is connected to the expansion generator (42) through the three-way valve (44).

5. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 1, characterized in that, The medium-deep ground-source high-efficiency carbon dioxide thermal energy harvesting and conversion system includes: An auxiliary air source heat exchanger (5) is connected to the input end of the throttling component (34) and the K8 port for cooling the heat exchange medium.

6. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 2, characterized in that, The medium-deep ground-source high-efficiency carbon dioxide thermal energy harvesting and conversion system includes: The control system is electrically connected to the ground energy hub module (3) and the integrated power generation and regeneration module (4), and is also electrically connected to the power grid dispatching system.

7. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 2, characterized in that, The medium-deep ground-source high-efficiency carbon dioxide thermal energy harvesting and conversion system includes: A switching valve (6) is located between the input end of the integrated power generation and regeneration module (4) and the output end of the user-side heat exchanger (33); In the heating mode, the switch valve (6) is open; in the cooling mode, the switch valve (6) is closed.

8. The high-efficiency thermal energy harvesting and conversion system for medium-deep ground-source carbon dioxide according to claim 1, characterized in that, The outer peripheral walls of both the inner tube (22) and the outer tube (21) are provided with fins.

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