A shallow geothermal energy, solar energy, phase change energy storage multi-energy coupling heating system

Abstract

The application discloses a shallow geothermal energy, solar energy, phase change energy storage multi-energy coupling heating system and relates to the technical field of clean energy comprehensive heating. The system comprises a geothermal energy utilization system, a solar energy heat collection system, a phase change energy storage system and an intelligent control system; the phase change energy storage water tank is connected in parallel with a ground source side heat exchange loop through an energy storage branch pipeline and the medium flow direction is controlled through a valve; an electric heater is arranged in the phase change energy storage water tank and is used for auxiliary heating. The application utilizes solar energy to heat the phase change energy storage water tank, assists the ground source heat pump in heating through phase change latent heat in winter, solves the problem of soil heat imbalance of the traditional ground source heat pump and realizes cross-season energy storage by backfilling the excess solar heat into the ground in summer. The system realizes efficient cooperation of the geothermal energy, the solar energy and the phase change energy storage through an intelligent control strategy, has the advantages of high energy utilization rate, low operation cost, remarkable environmental protection benefit and the like and is suitable for clean heating demands of various buildings.

Description

Technical Field

[0001] This invention belongs to the field of clean energy integrated heating technology, specifically relating to a multi-energy coupled heating system that combines shallow geothermal energy, solar energy, and phase change energy storage. Background Technology

[0002] As the energy structure transformation in the heating sector accelerates, the government has introduced a series of policies to encourage an increase in the proportion of renewable energy in heating, gradually replacing scattered coal and traditional high-energy-consuming heating methods.

[0003] However, the independent application of any single clean energy technology for heating faces significant technical and economic bottlenecks: shallow geothermal energy (ground source heat pump) systems operate stably, but have high initial investment costs, with the cost of underground pipe drilling accounting for a large proportion; and are limited by geological conditions, with limited applicability in areas with poor soil thermal conductivity or limited space; more importantly, in areas primarily for heating, long-term single-season heat extraction leads to a gradual decrease in soil temperature year by year, resulting in a continuous decline in the system's energy efficiency ratio, i.e., the problem of "soil cold accumulation," requiring additional heating measures to maintain system performance. Although solar thermal systems are clean and renewable, they have inherent intermittency and instability, with heat supply significantly affected by day and night, season, and weather, unable to provide a continuous and stable heat source, requiring reliance on large-capacity heat storage or auxiliary heat sources; in winter, weak solar irradiance and short sunshine hours result in low heat collection efficiency, creating a sharp contradiction with peak heating demand; and to meet high solar energy guarantee rates, a large heat collection area is required, leading to a long initial investment payback period.

[0004] Existing multi-energy complementary heating systems mostly use air source heat pumps as a supplementary heat source for solar energy. However, in the extreme low-temperature environment of Northwest China during winter, such as -20℃ and below, air source heat pumps suffer from technical bottlenecks such as frequent frosting, severe reduction in heating capacity, and a sharp drop in energy efficiency ratio. At the same time, traditional energy storage devices mostly use ordinary water storage tanks, which have low energy density, large volume, and continuous temperature drop during heat release, making it difficult to maintain a stable heating water temperature.

[0005] Therefore, there is an urgent need to develop a new type of multi-energy coupled heating system that does not rely on air source heat pumps, can achieve efficient supplementary heating through phase change energy storage and electric heating, and has a unique cycle control strategy for solar ice melting and energy storage, in order to solve the technical problems existing in the current technology, such as unbalanced cold and heat loads, poor heating stability under extreme conditions, and low energy storage density. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-energy coupled heating system that combines shallow geothermal energy, solar energy, and phase change energy storage. By constructing a triple complementary architecture with geothermal energy as the basic heat source, solar energy as the auxiliary heat source, and phase change energy storage as the regulation hub, the heating system can achieve stable operation throughout the year and in all weather conditions, maximize comprehensive energy efficiency, and significantly reduce carbon emissions.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A multi-energy coupled heating system for shallow geothermal energy, solar energy, and phase change energy storage includes a geothermal energy utilization system, a solar thermal collection system, a phase change energy storage system, and an intelligent control system.

[0009] The geothermal energy utilization system includes a geothermal heat exchanger and a ground source heat pump unit. The geothermal heat exchanger is connected to the ground source heat pump unit through a ground source-side circulation pipeline to form a ground source-side circulation loop. The ground source heat pump unit is also connected to the user side through a user-side circulation pipeline to form a heating loop.

[0010] The solar thermal collection system includes solar PV / T modules and solar PT modules. The solar PV / T modules are integrated photovoltaic and solar thermal modules, used to simultaneously generate electricity and heat. The solar PT modules are pure solar thermal modules. The solar PV / T modules and solar PT modules are connected in parallel and then connected to a phase change energy storage tank through a heat energy circulation pipeline to form a heat energy circulation loop, used for heat exchange with the phase change energy storage system and the geothermal energy utilization system.

[0011] The phase change energy storage system includes a phase change energy storage tank and an electric heater. The phase change energy storage tank is connected in parallel to the ground source side circulation loop via a ground source side energy storage branch pipeline. The phase change energy storage tank is filled with phase change energy storage material, utilizing the latent heat of the phase change material during the solid-liquid phase change process for high-density heat storage and isothermal heat release. The electric heater is built into the phase change energy storage tank to provide auxiliary heat energy when solar radiation is insufficient, enabling ice melting energy storage or supplementary heating.

[0012] The intelligent control system includes temperature sensors, electric valves, and a central controller. The temperature sensors include a T1 temperature sensor for monitoring the temperature of the solar PV / T and solar PT modules, and a T2 temperature sensor for monitoring the temperature of the phase change energy storage tank. The electric valves include an M1 electric valve for controlling the bypass of the buried pipe directly connected to the evaporator, and an M2 electric valve for controlling the flow of the circulating medium through the phase change energy storage tank. The central controller dynamically adjusts the opening degree of the M1 and M2 electric valves and the start / stop of each circulating pump based on the temperature signals from the T1 and T2 temperature sensors and the return water temperature on the user side.

[0013] The ground-source circulation loop, the heating loop, and the thermal energy circulation loop are all equipped with circulation pumps, and the solar PV / T modules provide electrical energy to each of the circulation pumps.

[0014] Furthermore, the geothermal heat exchanger is a double U-shaped buried pipe heat exchanger, and the ground source heat pump unit includes a condenser, an evaporator, and a compressor;

[0015] Multiple double-U-shaped buried pipe heat exchangers are buried underground. The rising sections of the multiple double-U-shaped buried pipe heat exchangers are connected in parallel and then connected to the water collector and the ground source medium inlet of the evaporator through a first ground source side circulation pipeline. A ground source side circulation pump is installed on the first ground source side circulation pipeline. The falling sections of the multiple double-U-shaped buried pipe heat exchangers are connected in parallel and then connected to the water distributor and the ground source medium outlet of the evaporator through a second ground source side circulation pipeline.

[0016] The refrigerant outlet of the evaporator is connected in sequence to the compressor and the refrigerant inlet of the condenser via a refrigerant pipeline, and the refrigerant outlet of the condenser is connected to the refrigerant inlet of the evaporator via a refrigerant pipeline;

[0017] The user-side medium inlet and user-side medium outlet of the condenser are respectively connected to the user side via the user-side circulation pipeline, and a user-side circulation pump is installed on the user-side circulation pipeline between the user-side medium inlet and the user side.

[0018] Furthermore, the M1 electric valve is installed on the first ground source side circulation pipeline between the ground source side circulation pump and the evaporator; one interface of the phase change energy storage tank is connected to the first ground source side circulation pipeline between the M1 electric valve and the evaporator through the first ground source side energy storage branch pipeline, and the other interface is connected to the second ground source side circulation pipeline between the water distributor and the evaporator through the second ground source side energy storage branch pipeline, and the M2 electric valve is installed on the second ground source side energy storage branch pipeline.

[0019] Furthermore, when the M1 electric valve is open, the ground source medium from the outlet side of the ground source circulating pump directly enters the evaporator through the ground source circulating pipeline; when the M1 electric valve is closed or in the regulating state, the ground source medium from the outlet side of the ground source circulating pump is heated by the phase change energy storage tank before entering the evaporator, and the M1 electric valve is electrically connected to the intelligent control system.

[0020] Furthermore, when the return water temperature on the user side is lower than a preset threshold, the M2 electric valve opens, and a portion of the circulating medium flowing out of the evaporator of the ground source heat pump unit extracts the sensible and latent heat of the phase change energy storage material through the coil heat exchanger in the phase change energy storage tank, and then returns to the evaporator to release heat.

[0021] Furthermore, the power output terminal of the solar PV / T module is sequentially connected to a combiner box, an inverter, and an energy storage device. Excess electricity generated by the solar PV / T module is converted from DC to AC by the inverter through the combiner box and then stored in the energy storage device. The power output terminal of the energy storage device is electrically connected to the electric heater and each of the circulating pumps, prioritizing the heating of water in the phase change energy storage tank by the electric heater. Excess electricity is stored in the energy storage device or connected to the grid.

[0022] Furthermore, the phase change energy storage material in the phase change energy storage tank is an inorganic hydrated salt phase change material or a paraffin-based organic phase change material, and the phase change temperature is 15℃~30℃.

[0023] Furthermore, the pipe material of the double U-shaped buried pipe heat exchanger is De32 PE pipe, and the burial depth is 150-250 meters.

[0024] The present invention also discloses the working method of the above-mentioned shallow geothermal energy, solar energy and phase change energy storage multi-energy coupled heating system, including winter heating mode and summer heat storage mode;

[0025] Under the aforementioned winter heating mode,

[0026] No solar radiation: The central controller controls the M1 electric valve to be fully open and the M2 electric valve to be closed. The circulating medium in the buried pipe is directly sent to the evaporator, and the building heating is completed independently by relying on shallow geothermal energy.

[0027] Daytime solar thermal collector operation: When the T1 temperature sensor reaches the first preset value, the solar side circulation pump is started. The solar PV / T module and the solar PT module absorb solar radiation heat to heat the phase change energy storage tank. The solar PV / T module generates and stores electricity simultaneously.

[0028] Phase change preheating ground source medium working condition: When the temperature monitored by the T2 temperature sensor reaches the second preset value, the central controller linearly closes the M1 electric valve and opens the M2 electric valve. The ground source medium is diverted into the phase change energy storage tank for preheating and then flows into the evaporator. The closed-loop regulating valve opening keeps the evaporator inlet water temperature stable below 25℃.

[0029] Extreme cold peak shaving conditions: When the return water temperature on the user side is less than the third preset value, the M1 electric valve and the M2 electric valve are opened simultaneously and fully. The ground source medium absorbs heat in parallel on both sides, and the phase change energy storage material releases latent heat to supplement the heating. After the phase change energy storage material solidifies, the power of the energy storage device is used to drive the electric heater to melt the phase change energy storage material to complete the secondary heat storage.

[0030] Furthermore, in the summer heat storage mode, the ground source heat pump unit and the user-side heating cycle are shut down, the M1 electric valve is closed, and the M2 electric valve is opened;

[0031] When the temperature monitored by the T1 temperature sensor reaches the fourth preset value, the solar side circulation pump is started, the solar thermal system stores heat in the phase change energy storage tank, and the electric heater is started as needed to supplement heat.

[0032] When the temperature monitored by the T2 temperature sensor reaches the fifth preset value, the ground source side circulation pump is started, and all the circulating medium in the buried pipe flows through the phase change energy storage tank to absorb heat. The heat in the phase change energy storage tank is stored in the underground rock and soil through the double U-shaped buried pipe heat exchanger.

[0033] When either the T1 temperature sensor reaches the fourth preset value or the T2 temperature sensor reaches the fifth preset value, the ground source side circulation pump is forcibly started to remove the waste heat from the solar thermal system, limiting the operating temperature of the solar thermal system to no more than 40°C throughout the year and stabilizing the photoelectric conversion efficiency.

[0034] The present invention has the following beneficial effects:

[0035] 1. This invention uses a phase change energy storage tank to replace an ordinary energy storage tank. It utilizes the characteristic of phase change energy storage materials to store / release a large amount of latent heat during the solid-liquid phase change process. The heat storage density is significantly improved compared with traditional sensible heat storage. More heat can be stored in the same volume, effectively suppressing the intermittent fluctuations of solar heating and realizing cross-time heat energy allocation.

[0036] 2. This invention provides a stable base load through geothermal energy, with solar energy dominating daytime power supply, and phase change energy storage precisely regulating peak loads during low temperatures or nighttime periods, forming 24-hour full-time coverage. In summer, the system can utilize excess solar energy to reinject heat into the underground soil, effectively solving the soil thermal imbalance problem caused by long-term heat extraction in traditional ground source heat pump systems, and ensuring long-term efficient operation of the system;

[0037] 3. This invention ensures the continuity and stability of heating through the intelligent linkage of temperature sensors T1 and T2 with electric valves M1 and M2. Simultaneously, the system employs intelligent dynamic optimization control, automatically switching heat sources to maximize overall energy efficiency. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0039] 1-Ground source heat pump unit; 2-Double U-shaped buried pipe heat exchanger; 3-Solar PV / T module; 4-Solar PT module; 5-Phase change energy storage tank; 6-Water collector; 7-Water distributor; 8-Electric heater; 9-User-side circulation pump; 10-Ground source-side circulation pump; 11-Solar-side circulation pump; 12-Combiner box; 13-Inverter; 14-Energy storage device; 15-T1 temperature sensor; 16-T2 temperature sensor; 17-M1 electric valve; 18-M2 electric valve. Detailed Implementation

[0040] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figure 1 As shown, a shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system provided by the present invention includes a geothermal energy utilization system, a solar thermal collection system, a phase change energy storage system, and an intelligent control system.

[0042] In this embodiment, the geothermal energy utilization system includes a double U-shaped buried pipe heat exchanger 2 and a ground source heat pump unit 1. The double U-shaped buried pipe heat exchanger 2 is connected to the ground source heat pump unit through a ground source side circulation pipeline to form a ground source side circulation loop. The ground source heat pump unit is also connected to the user side through a user side circulation pipeline to form a heating loop.

[0043] Specifically, the solar thermal system includes solar PV / T modules 3 and solar PT modules 4. The solar PV / T modules are integrated photovoltaic and solar thermal modules used to simultaneously generate electricity and heat; the solar PT modules are pure solar thermal modules. The solar PV / T modules and solar PT modules are connected in parallel and then connected to a phase change energy storage tank via a heat circulation pipeline to form a heat circulation loop, used for heat exchange with the phase change energy storage system and the geothermal energy utilization system. The solar PV / T modules 3 and solar PT modules 4 are preferably installed in a rooftop integrated manner to achieve the triple functions of "power generation + heat collection + shading".

[0044] The phase change energy storage system includes a phase change energy storage tank 5 and an electric heater 8. The phase change energy storage tank 5 is connected in parallel with the ground source heat pump unit 1 through a ground source-side energy storage branch pipeline. The phase change energy storage tank is filled with inorganic hydrated salt phase change material or paraffin-based organic phase change material, with a phase change temperature of 15℃~30℃. It utilizes the latent heat of the phase change material during the solid-liquid phase change process for high-density heat storage and isothermal heat release. The electric heater is built into the phase change energy storage tank to provide auxiliary heat energy when solar radiation is insufficient, realizing ice melting energy storage or supplementary heating.

[0045] The intelligent control system includes temperature sensors, electric valves, and a central controller. The temperature sensors include a T1 temperature sensor 15 for monitoring the temperature of the solar PV / T module 3 and the solar PT module 4, and a T2 temperature sensor 16 for monitoring the temperature of the phase change energy storage tank 5. The electric valves include an M1 electric valve 17 for controlling the bypass of the buried pipe directly connected to the evaporator, and an M2 electric valve 18 for controlling the flow of the circulating medium through the phase change energy storage tank. The central controller dynamically adjusts the opening degree of the M1 electric valve 17 and the M2 electric valve 18, as well as the start and stop of each circulating pump, based on the temperature signals from the T1 and T2 temperature sensors 16 and the return water temperature on the user side.

[0046] The ground source side circulation loop, heating loop, and thermal energy circulation loop are all equipped with circulation pumps, and the solar PV / T module 3 provides power to each circulation pump.

[0047] In this embodiment, the ground source heat pump unit 1 includes a condenser, an evaporator, and a compressor; the double U-shaped buried pipe heat exchanger 2 uses De32 PE pipe and is buried at a depth of 200 meters. Multiple double U-shaped buried pipe heat exchangers are buried below ground level. The rising sections of these heat exchangers are connected in parallel and then connected to the water collector 6 and the ground source medium inlet of the evaporator via a first ground source-side circulation pipeline. A ground source-side circulation pump is installed on the first ground source-side circulation pipeline. The descending sections of these heat exchangers are connected in parallel and then connected to the water distributor 7 and the ground source medium outlet of the evaporator via a second ground source-side circulation pipeline.

[0048] The refrigerant outlet of the evaporator is connected to the refrigerant inlet of the compressor and the condenser in sequence through a refrigerant pipeline, and the refrigerant outlet of the condenser is connected to the refrigerant inlet of the evaporator through a refrigerant pipeline;

[0049] The user-side medium inlet and user-side medium outlet of the condenser are connected to the user side via user-side circulation pipelines. A user-side circulation pump 9 is installed on the user-side circulation pipeline between the user-side medium inlet and the user side.

[0050] In this embodiment, the M1 electric valve 17 is installed on the first ground source side circulation pipeline between the ground source side circulation pump 10 and the evaporator; one interface of the phase change energy storage tank 5 is connected to the first ground source side circulation pipeline between the M1 electric valve 17 and the evaporator through the first ground source side energy storage branch pipeline, and the other interface is connected to the second ground source side circulation pipeline between the water distributor 7 and the evaporator through the second ground source side energy storage branch pipeline; the M2 electric valve 18 is installed on the second ground source side energy storage branch pipeline.

[0051] In this embodiment, when the M1 electric valve 17 is open, the ground source medium from the outlet side of the ground source circulating pump 10 directly enters the evaporator through the ground source circulating pipeline; when the M1 electric valve 17 is closed or in the regulating state, the ground source medium from the outlet side of the ground source circulating pump 10 is heated by the phase change energy storage tank before entering the evaporator. The M1 electric valve is electrically connected to the intelligent control system.

[0052] In this embodiment, when the return water temperature on the user side is lower than the preset threshold, the M2 electric valve opens, and a portion of the circulating medium flowing out of the evaporator of the ground source heat pump unit extracts the sensible and latent heat of the phase change energy storage material through the coil heat exchanger in the phase change energy storage tank, and then returns to the evaporator to release heat.

[0053] In this embodiment, the power output terminal of the solar PV / T module 3 is sequentially connected to the combiner box 12, the inverter 13, and the energy storage device 14. Excess power generated by the solar PV / T module is stored in the energy storage device 14 after being converted from DC to AC by the inverter 13 through the combiner box 12. The power output terminal of the energy storage device 14 is electrically connected to the electric heater 8 and each circulation pump, prioritizing the heating of water in the phase change energy storage tank 5 by the electric heater. Excess power is stored in the energy storage device 14 or connected to the grid.

[0054] The heating and heat storage method of the multi-energy coupled heating system provided by the present invention includes a winter heating mode and a summer heat storage mode.

[0055] At the beginning of the heating season, the heat extracted from the underground soil and rock by the double U-shaped buried pipe heat exchanger 2 is used as the heat source of the ground source heat pump unit 1. The U-shaped circulation process of the double U-shaped buried pipe heat exchanger has a descending section and an ascending section. After the circulating medium extracts heat from the soil and rock through circulation, it enters the water collector 6, passes through the ground source side circulation pump 10, and enters the evaporator of the ground source heat pump unit 1. After the heat pump unit extracts and transfers energy, the cooled circulating medium enters the water distributor 7, and then enters the double U-shaped buried pipe heat exchanger 2 to extract heat from the soil and rock again, completing the ground source side heat extraction and release cycle.

[0056] In the ground source heat pump unit 1, the refrigerant absorbs heat in the evaporator, and then the refrigerant is transformed into a high-temperature and high-pressure gas by the compressor. It enters the condenser and releases heat to the user-side circulation medium. After the refrigerant releases heat in the condenser, it enters the throttling device. After the throttling effect, the refrigerant is transformed into a low-temperature and low-pressure gas-liquid mixture, and then enters the evaporator to continue absorbing heat, thus completing the refrigerant cycle.

[0057] After the user-side circulating medium absorbs heat from the condenser, it enters the heat user's heating supply. After cooling down by supplying heat to the heat user, the circulating medium returns to the condenser of the ground source heat pump unit 1 via the user-side circulating pump 9 to continue heat exchange, thus completing the user-side heating cycle.

[0058] The phase change energy storage tank 5 is connected in parallel with the ground source heat pump unit 1 to supplement the heating energy. The system uses the buried pipe heat exchange system to a limited extent. When the heating temperature cannot meet the demand or the water in the phase change energy storage tank 5 is heated to the set value by the solar modules, the phase change energy storage tank 5 starts to supplement the system with heat to avoid excessive heat extraction and heat imbalance in the underground rock and soil.

[0059] Winter operating mode:

[0060] Electric valve 17 M1 opens automatically, and electric valve 18 M2 closes, allowing the circulating medium from the buried pipe to directly enter the evaporator of the heat pump unit as a heat source.

[0061] When the temperature of temperature sensor 15 reaches 30℃, the solar side circulation pump 11 is turned on by the control system. At this time, the solar PV / T module 3 and solar PT module 4 absorb solar radiation heat energy and heat the water in phase change energy storage tank 5 through the intermediate medium. The solar PV / T module and solar PT module are respectively connected to the coil heat exchanger in the phase change energy storage tank.

[0062] When the water in the phase change energy storage tank 5 is heated, and the temperature sensor 16 of T2 reaches 15°C, the electric valve 17 of M1 automatically adjusts until it closes. The opening degree of the electric valve 17 of M1 changes with the temperature of the circulating medium entering the evaporator of the ground source heat pump unit 1, and always keeps the temperature of the circulating water entering the evaporator below 25°C. At this time, the circulating medium driven by the ground source side circulation pump 10 enters the phase change energy storage tank 5 and is heated. Then it enters the evaporator of the ground source heat pump unit 1 to complete the ground source side heat extraction cycle of solar-assisted heating.

[0063] The solar PV / T module 3 generates both heat energy and DC power while receiving solar radiation. The DC power is converted into AC power by the inverter 13 through the combiner box 12 and stored in the energy storage device 14. The stored power is used to heat the water in the phase change energy storage tank 5 by the electric heater 8 as a supplement to the heat of the phase change energy storage tank. The electric heater 8 has a power of 7.5kW and operates for 2-3 hours in winter. The remaining power can then be used to supply the solar-side circulation pump 11, the ground-source side circulation pump 10, and other electrical equipment in the system. When the power is sufficient, it can also be connected to the grid and freely converted.

[0064] The system prioritizes the operation of the ground source heat pump unit 1. When the heat demand is insufficient, such as when the return water temperature on the user side is below 40℃, electric valves M1 (17) and M2 (18) open simultaneously. Part of the circulating medium from the evaporator of the ground source heat pump unit 1 enters the water distributor 7 and then the double U-shaped buried pipe heat exchanger 2 for heat extraction. Another part passes through electric valve M2 (18) and enters the coil heat exchanger in the phase change energy storage tank 5 to extract the sensible and latent heat of the water. After heat extraction, the circulating medium returns to the evaporator of the ground source heat pump unit 1 to release heat and provide a heat source for the unit, ensuring that the indoor temperature on the user side meets the design requirements. The phase change energy storage material in the phase change energy storage tank 5 changes from liquid to solid after phase change heat release. Then, the solar PV / T module 3 and solar PT module 4 absorb solar radiation to generate heat for ice melting and energy storage. When the solar heat is insufficient for melting, the electrical energy in the energy storage device 14 drives the electric heater 8 for ice melting.

[0065] Summer operating mode:

[0066] Close electric valve 17 (M1), open electric valve 18 (M2), and shut down ground source heat pump unit 1. Solar PV / T modules 3 and solar PT modules 4 absorb solar radiation and generate heat, causing the module temperature to rise. When temperature sensor 15 (T1) reaches 40°C, solar-side circulation pump 11 is activated to heat the water in phase change energy storage tank 5 using the heat generated by solar radiation. When temperature sensor 16 (T2) reaches 30°C, ground source circulation pump 10 is activated to transfer the heat from phase change energy storage tank 5 to double U-shaped buried pipe heat exchanger 2 via a circulating medium, replenishing the heat to the underground soil and rock to form an underground heat reservoir.

[0067] For every 1°C increase in the operating temperature of the solar PV / T module 3, the power generation efficiency will decrease by 0.3% to 0.5%. The maximum temperature does not exceed 40°C. Therefore, regardless of whether T1 or T2 reaches the set temperature first, the ground source side circulation pump 10 must be started to transfer the heat to the buried pipe heat exchange system for heat storage. This is a double protection for the power generation efficiency of the solar PV / T module 3.

[0068] The solar PV / T module 3 generates both heat and DC power. The DC power enters the combiner box 12 and is then converted into AC power by the inverter 13 and stored in the energy storage device 14. The stored power is used to heat the water in the phase change energy storage tank 5 by the electric heater 8 as a heat supplement to the phase change energy storage tank. The electric heater has a power of 7.5kW and operates for 3-4 hours in summer. The remaining power is used to power the solar-side circulation pump 11 and the ground-source circulation pump 10, reducing the system's consumption of municipal power grid power.

[0069] In summary, this invention provides a multi-energy coupled heating system integrating shallow geothermal energy, solar energy, and phase change energy storage. It innovatively proposes a winter heating technology route that does not rely on air-source heat pumps and a solar ice-melting energy storage control strategy, effectively solving technical problems in existing technologies such as unbalanced heating and cooling loads, unstable heating under extreme conditions, and low energy storage density. It possesses significant technological advancements, economic benefits, and environmental advantages.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-energy coupled heating system integrating shallow geothermal energy, solar energy, and phase change energy storage, characterized in that: This includes geothermal energy utilization systems, solar thermal collection systems, phase change energy storage systems, and intelligent control systems; The geothermal energy utilization system includes a geothermal heat exchanger and a ground source heat pump unit (1). The geothermal heat exchanger is connected to the ground source heat pump unit (1) through a ground source side circulation pipeline to form a ground source side circulation loop. The ground source heat pump unit (1) is also connected to the user side through a user side circulation pipeline to form a heating loop. The solar thermal system includes a solar PV / T module (3) and a solar PT module (4). The solar PV / T module (3) is an integrated photovoltaic and photothermal module used to generate electricity and heat simultaneously. The solar PT module (4) is a pure photothermal module. The solar PV / T module and the solar PT module are connected in parallel and then connected to a phase change energy storage tank through a heat energy circulation pipeline to form a heat energy circulation loop, which is used to exchange heat with the phase change energy storage system and the geothermal energy utilization system. The phase change energy storage system includes a phase change energy storage tank (5) and an electric heater (8). The phase change energy storage tank is connected in parallel with the ground source side circulation loop through a ground source side energy storage branch pipeline. The phase change energy storage tank is filled with phase change energy storage material, and the electric heater is built into the phase change energy storage tank. The intelligent control system includes temperature sensors, electric valves, and a central controller. The temperature sensors include a T1 temperature sensor (15) for monitoring the temperature of the solar PV / T module (3) and the solar PT module (4) and a T2 temperature sensor (16) for monitoring the temperature of the phase change energy storage tank (5). The electric valves include an M1 electric valve (17) for controlling the bypass of the buried pipe directly connected to the evaporator and an M2 electric valve (18) for controlling the flow of the circulating medium through the buried pipe into the phase change energy storage tank (5). The central controller dynamically adjusts the opening degree of the M1 electric valve (17) and the M2 electric valve (18) and the start and stop of each circulating pump according to the temperature signals of the T1 temperature sensor (15) and the T2 temperature sensor (16) and the return water temperature on the user side. The ground source circulation loop, the heating loop, and the thermal energy circulation loop are all equipped with circulation pumps, and the solar PV / T module (3) provides electrical energy to each of the circulation pumps.

2. The shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system according to claim 1, characterized in that: The geothermal heat exchanger is a double U-shaped buried pipe heat exchanger (2), and the ground source heat pump unit includes a condenser, an evaporator and a compressor; Multiple double U-shaped buried pipe heat exchangers (2) are buried below ground level. The rising sections of the multiple double U-shaped buried pipe heat exchangers (2) are connected in parallel and then connected to the water collector (6) and the ground source medium inlet of the evaporator through the first ground source side circulation pipeline. A ground source side circulation pump (10) is installed on the first ground source side circulation pipeline. The falling sections of the multiple double U-shaped buried pipe heat exchangers (2) are connected in parallel and then connected to the water distributor (7) and the ground source medium outlet of the evaporator through the second ground source side circulation pipeline. The refrigerant outlet of the evaporator is connected in sequence to the compressor and the refrigerant inlet of the condenser via a refrigerant pipeline, and the refrigerant outlet of the condenser is connected to the refrigerant inlet of the evaporator via a refrigerant pipeline; The user-side medium inlet and user-side medium outlet of the condenser are respectively connected to the user side via the user-side circulation pipeline, and a user-side circulation pump (9) is provided on the user-side circulation pipeline between the user-side medium inlet and the user side.

3. A shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system according to claim 2, characterized in that: The M1 electric valve (17) is installed on the first ground source side circulation pipeline between the ground source side circulation pump (10) and the evaporator; one interface of the phase change energy storage tank (5) is connected to the first ground source side circulation pipeline between the M1 electric valve (17) and the evaporator through the first ground source side energy storage branch pipeline, and the other interface is connected to the second ground source side circulation pipeline between the water distributor (7) and the evaporator through the second ground source side energy storage branch pipeline, and the M2 electric valve (18) is installed on the second ground source side energy storage branch pipeline.

4. A shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system according to claim 3, characterized in that: When the M1 electric valve (17) is open, the ground source medium from the outlet side of the ground source circulating pump (10) enters the evaporator directly through the ground source circulating pipeline; when the M1 electric valve (17) is closed or in the regulating state, the ground source medium from the outlet side of the ground source circulating pump (10) is heated by the phase change energy storage tank (5) before entering the evaporator. The M1 electric valve is electrically connected to the intelligent control system.

5. A shallow geothermal, solar, and phase change energy storage multi-energy coupled heating system according to claim 3, characterized in that: When the return water temperature on the user side is lower than the preset threshold, the M2 electric valve (18) opens, and a portion of the circulating medium flowing out of the evaporator of the ground source heat pump unit (1) extracts the sensible heat and latent heat of the phase change energy storage material through the coil heat exchanger in the phase change energy storage tank (5) and returns to the evaporator to release heat.

6. A shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system according to claim 1, characterized in that: The power output terminal of the solar PV / T module (3) is connected in sequence to the combiner box (12), the inverter (13) and the energy storage device (14). The excess power generated by the solar PV / T module (3) is passed through the combiner box (12) and converted from DC to AC by the inverter (13) and then stored in the energy storage device (14). The power output terminal of the energy storage device (14) is electrically connected to the electric heater (8) and each of the circulating pumps, giving priority to ensuring that the electric heater heats the water in the phase change energy storage tank, and the excess power is stored in the energy storage device or connected to the grid.

7. A shallow geothermal, solar, and phase change energy storage multi-energy coupled heating system according to claim 1, characterized in that: The phase change energy storage material in the phase change energy storage tank (5) is an inorganic hydrated salt phase change material or a paraffin-based organic phase change material, and the phase change temperature is 15℃~30℃.

8. A shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system according to claim 2, characterized in that: The pipe material of the double U-shaped buried pipe heat exchanger (2) is De32 PE pipe, and the burial depth is 150-250 meters.

9. A heating and heat storage method for a multi-energy coupled heating system, applied to the shallow geothermal energy, solar energy, and phase change energy storage multi-energy coupled heating system as described in any one of claims 1 to 8, characterized in that: This includes winter heating mode and summer heat storage mode; Under the aforementioned winter heating mode, No solar irradiation: The central controller controls the M1 electric valve (17) to be fully open and the M2 electric valve (18) to be closed. The underground pipe circulation medium is directly sent into the evaporator, and the building heating is completed independently by relying on shallow geothermal heat. During daytime solar thermal operation: When the T1 temperature sensor (15) reaches the first preset value, the solar side circulation pump (11) is started, and the solar PV / T module (3) and solar PT module (4) absorb solar radiation heat to heat the phase change energy storage tank (5), and the solar PV / T module (3) generates and stores electricity synchronously. Phase change preheating ground source medium working condition: T2 temperature sensor (16) monitors the temperature to reach the second preset value, the central controller linearly closes M1 electric valve (17) and opens M2 electric valve (18), the ground source side medium is diverted into the phase change energy storage tank (5) and then flows into the evaporator after preheating, the valve opening is closed to make the evaporator inlet water temperature stable below 25℃. Extreme cold peak shaving conditions: When the return water temperature on the user side is less than the third preset value, the M1 electric valve (17) and the M2 electric valve (18) are opened simultaneously and fully. The ground source medium absorbs heat in parallel on both sides, and the phase change energy storage material releases latent heat to supplement the heating. After the phase change energy storage material solidifies, the power of the energy storage device is used to drive the electric heater (8) to melt the phase change energy storage material and complete the secondary heat storage.

10. The heating and heat storage method of a multi-energy coupled heating system according to claim 9, characterized in that: In the summer heat storage mode, the ground source heat pump unit (1) and the user-side heating cycle are shut down, the M1 electric valve (17) is closed, and the M2 electric valve (18) is opened. When the temperature monitored by the T1 temperature sensor (15) reaches the fourth preset value, the solar side circulation pump (11) is started, the solar thermal system stores heat in the phase change energy storage tank (5), and the electric heater (8) is started as needed to supplement the heat. When the temperature monitored by the T2 temperature sensor (16) reaches the fifth preset value, the ground source side circulation pump (10) is started. All the circulating medium of the buried pipe flows through the phase change energy storage tank (5) to absorb heat. The heat in the phase change energy storage tank (5) is stored in the underground rock and soil through the double U-shaped buried pipe heat exchanger (2). The T1 temperature sensor (15) is triggered when it reaches the fourth preset value or the T2 temperature sensor (16) reaches the fifth preset value. The ground source side circulation pump (10) is then forcibly started to remove the waste heat from the solar thermal system. The working temperature of the solar thermal system is limited to no more than 40°C throughout the year to stabilize the photoelectric conversion efficiency.

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