Solar energy cross-season soil energy storage heating and power generation integrated system based on expansion compressor

Abstract

The application discloses a solar cross-season soil energy storage heating and power generation integrated system based on an expansion compressor, and the system comprises a working medium pump, a solar collector, an evaporator, an expansion compressor, a permanent magnet motor, a condenser and a buried pipe. In the power generation mode, the working medium pump is opened; heat generated by the solar collector enters the evaporator to evaporate liquid refrigerant; gaseous refrigerant drives the expansion compressor to work and drives the permanent magnet motor to generate electricity; gaseous refrigerant after work enters the condenser to exchange heat with circulating water in the buried pipe and is condensed; heat not converted into electric energy is stored in the soil through the buried pipe; and liquid refrigerant after condensation is pumped back to the evaporator by the working medium pump. In the heating mode, the permanent magnet motor is electrified and drives the expansion compressor; heat generated by the solar collector and soil heat extracted by the buried pipe jointly enter the evaporator to evaporate liquid refrigerant; gaseous refrigerant is compressed into high-temperature gaseous refrigerant by the expansion compressor and then enters the condenser to exchange heat with a user end heating pipe network and is condensed; and liquid refrigerant after condensation flows into the evaporator after pressure reduction by an expansion valve.

Description

Technical Field

[0001] This invention patent relates to the field of solar energy utilization, and in particular to an integrated solar energy cross-seasonal soil energy storage heating and power generation system based on an expansion compressor. Background Technology

[0002] Solar energy is a renewable and clean energy source with abundant reserves. Its development and utilization are considered one of the important paths to solve energy shortages and promote low-carbon development. Currently, the main ways to utilize solar energy include: solar thermal power generation, which uses solar collectors to convert solar energy into heat energy or uses mirrors or lenses to concentrate sunlight and heat the working fluid to generate steam to drive turbines to generate electricity; photovoltaic power generation, which uses solar panels to convert solar energy into electrical energy; and photochemical utilization, which uses specific photocatalytic materials to convert solar energy into the kinetic energy of chemical reactions.

[0003] Because solar energy is greatly affected by meteorological conditions and has uneven temporal distribution, there are two main problems in its utilization: First, solar energy utilization lacks stability and is greatly affected by seasonal and meteorological factors. The current main solution is to use other forms of energy to form a multi-energy complementary system with solar energy. Second, the uneven temporal distribution of solar energy does not match the energy consumption trends of production and daily life. This leads to a large amount of "wasted energy" in some solar energy utilization equipment during high-production periods, while facing insufficient supply during low-production periods. The current main solution is to promote the cross-seasonal use of solar energy through thermal storage technologies such as phase change energy storage, soil energy storage, and hydroelectric energy storage.

[0004] The integrated compressor-expander is a device based on a permanent magnet motor that can compress the working fluid and generate electricity through the evaporation and expansion of the working fluid when electrical energy is input. Its working principle is as follows: when electrical energy is input, the device acts as a compressor in a reverse Carnot cycle, and the system functions as a heat pump heating system, enabling the upgrading of low-grade heat energy; when no power is supplied, the device acts as an expander in an organic Rankine cycle, and the system functions as a low-temperature heat source power generation system, utilizing low-temperature heat sources to generate electricity. This device has been applied to the utilization of low-temperature heat energy. During the non-heating season, the integrated unit acts as an expander, enabling the system to generate electricity from low-temperature heat energy and supply power to the outside world. During the heating season, the integrated unit acts as a compressor, enabling the system to upgrade the quality of low-temperature heat sources and supply heat energy to the outside world. This achieves year-round utilization of low-temperature heat energy and improves utilization efficiency. However, due to the technical limitations of the organic Rankine cycle, its efficiency can only reach about 8%. During the non-heating season, a large portion of the system's heat needs to be released into the atmosphere, resulting in energy waste. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies by applying integrated compression-expansion machine technology to the utilization of solar energy. Solar energy is used as a low-temperature heat source to drive the system, achieving a year-round dual-mode output of heat and power. Furthermore, the invention optimizes the system to address the main problems existing with integrated compression-expansion machines in solar energy utilization systems, providing a solar-powered, cross-seasonal soil storage heating and power generation integrated system based on integrated compression-expansion machines. This improves the solar energy utilization efficiency during the non-heating season and the overall operating efficiency of the heat pump heating system during the heating season, thereby enhancing the year-round operating efficiency of the integrated system, breaking through the limitations of traditional application scenarios, and providing a new technical solution for the cross-seasonal utilization of solar energy.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An integrated solar-powered cross-seasonal soil energy storage heating and power generation system based on an expansion compressor includes an expansion compressor, a permanent magnet motor, an evaporator, a condenser, an expansion valve, a working fluid pump, a solar collector, and buried pipes; the piping of the integrated system is divided into a refrigerant common pipeline A, a heating season open pipeline B, a non-heating season open pipeline C, and a solar collector pipeline D.

[0008] In power generation mode during the non-heating season: the circulation pipeline consists of the refrigerant common pipeline A, the non-heating season open pipeline C, and the solar collector pipeline D, and the working fluid pump is turned on; the heat generated by the solar collector enters the evaporator to evaporate the liquid refrigerant, and the gaseous refrigerant drives the expansion compressor, which acts as an expander, to do work and drive the permanent magnet motor to generate electricity; the gaseous refrigerant after doing work enters the condenser to exchange heat with the circulating water in the buried pipe and condenses, and the heat that is not converted into electrical energy is stored in the soil through the buried pipe; the condensed liquid refrigerant is pumped back to the evaporator by the working fluid pump.

[0009] During the heating season in heating mode: the circulation pipeline consists of the refrigerant common pipeline A, the heating season open pipeline B, and the solar collector pipeline D; the permanent magnet motor is energized and drives the expansion compressor, which operates as a compressor; the heat generated by the solar collector and the soil heat extracted by the buried pipe together serve as a low-temperature heat source and enter the evaporator, causing the liquid refrigerant to evaporate; the gaseous refrigerant is compressed into a high-temperature gaseous refrigerant by the expansion compressor and then enters the condenser, where it exchanges heat with the user's heating network and condenses; the condensed liquid refrigerant is depressurized by the expansion valve and then flows into the evaporator.

[0010] Furthermore, it also includes a hot water storage tank, which is connected to the solar collector and is positioned between the solar collector and the evaporator as a buffer.

[0011] Furthermore, the hot water storage tank is equipped with a flow divider to promote water stratification based on density differences; and the hot water storage tank is equipped with a water inlet for connecting to the municipal water network.

[0012] Furthermore, the system is equipped with sensors distributed at each node to collect real-time data on the solar collector outlet temperature, the lower outlet temperature of the hot water storage tank, the supply / return water temperature of the buried pipe, the heating temperature at the user end, the return water temperature at the user end, the pressure inside the evaporator, and the pressure inside the condenser; and temperature sensors are installed near the buried pipe to monitor soil temperature changes to prevent soil thermal imbalance.

[0013] Furthermore, each pipeline is equipped with several control valves and circulation pumps. The switching between the refrigerant common pipeline A, the heating season open pipeline B, and the non-heating season open pipeline C is achieved by shutting down each control valve.

[0014] Furthermore, the refrigerant common pipeline A includes a condenser, an expansion compressor, and an evaporator connected in sequence.

[0015] Furthermore, the heating season start-up pipeline B includes an expansion compressor and a permanent magnet motor connected to each other, as well as a condenser, an expansion valve and an evaporator connected in sequence. The evaporator is connected to the underground pipe through two pipelines, and the condenser is connected to the user end through two pipelines.

[0016] Furthermore, the non-heating season start-up pipeline C includes an expansion compressor, a permanent magnet motor and a user end connected in sequence, as well as a condenser, a working fluid pump and an evaporator connected in sequence. The condenser is connected to the underground pipe through two pipelines.

[0017] Furthermore, the solar collector pipeline D includes an evaporator, a hot water storage tank, and a solar collector connected in sequence.

[0018] The present invention also provides an operation method for the solar cross-seasonal soil energy storage heating and power generation integrated system, the operation method including heating mode operation steps during the heating season and power generation mode operation steps during the non-heating season;

[0019] During the heating season, the following steps shall be taken to operate the heating mode:

[0020] In step S11, the solar collector converts solar energy into thermal energy to heat the circulating water in the collector. The hot water flows into the evaporator through the hot water storage tank. At the same time, the circulating water in the underground pipe carries out the heat stored in the soil during the non-heating season and flows into the evaporator.

[0021] In step S12, the hot water from the solar collector and the hot water from the buried pipe work together as a low-temperature heat source to exchange heat with the low-temperature liquid refrigerant in the evaporator, so that the liquid refrigerant absorbs heat and evaporates into a low-temperature gaseous refrigerant.

[0022] In step S13, the low-temperature gaseous refrigerant is compressed into a high-temperature gaseous refrigerant by the expansion compressor and then flows into the condenser.

[0023] In step S14, the high-temperature gaseous refrigerant exchanges heat with the user's heating return water in the condenser and condenses. After the user's heating return water is heated, it flows into the user's heating network.

[0024] In step S15, the high-temperature liquid refrigerant generated by condensation flows through the expansion valve, causing a pressure drop and a decrease in temperature, before flowing back into the evaporator to complete the heat pump heating cycle based on the reverse Carnot cycle.

[0025] During the non-heating season, the following steps will be taken to operate in power generation mode:

[0026] In step S21, the solar collector converts solar energy into thermal energy, and the hot water flows into the evaporator through the hot water storage tank.

[0027] In step S22, the hot water from the solar collector exchanges heat with the low-temperature liquid refrigerant in the evaporator. The liquid refrigerant absorbs heat and evaporates, producing gaseous refrigerant and increasing the pressure inside the evaporator.

[0028] In step S23, the gaseous refrigerant expands and does work on the expansion compressor, driving the permanent magnet motor to convert mechanical energy into electrical energy and deliver it to the user end;

[0029] In step S24, the gaseous refrigerant after doing work flows into the condenser and condenses by exchanging heat with the circulating water in the underground pipe; the circulating water in the condenser, after being heated, exchanges heat with the soil through the underground pipe, storing the heat that has not been converted into electrical energy in the soil.

[0030] In step S25, the liquid refrigerant generated by condensation is pumped back to the evaporator by the working fluid pump, completing the low-temperature power generation cycle based on the organic Rankine cycle.

[0031] The operation method also includes system monitoring and control steps: real-time acquisition of solar collector outlet temperature, hot water storage tank lower outlet temperature, buried pipe supply and return water temperature, user-end heating temperature, user-end return water temperature, and pressure parameters in the evaporator and condenser; real-time monitoring of soil temperature using temperature sensors installed near the buried pipe, and determination of soil thermal imbalance based on annual soil temperature change trends; recording system operation parameter datasets under different modes using an online simulation platform, and combining the soil thermal imbalance determination results with the variable frequency drive and various control valves to dynamically adjust system operation.

[0032] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0033] 1. This invention employs a dual-mode approach combining an expansion compressor and solar thermal collection to address the problems of energy wastage and insufficient supply caused by uneven temporal distribution of solar energy, as well as the low utilization rate of single heating equipment during the off-season due to idleness. It achieves year-round dual-mode output of solar energy for both heat and power. During the off-season, electricity is generated through an organic Rankine cycle to provide power to the outside world; during the heating season, a heat pump heating cycle is used to improve the utilization of low-temperature heat sources, significantly expanding the application scope of solar energy utilization, improving the overall annual utilization efficiency of the equipment, and providing a new way to match solar energy with energy consumption demand.

[0034] 2. This invention couples buried pipes with a condenser during the non-heating season (power generation mode), solving the problem that traditional Organic Rankine Cycle (ORC) technology has an efficiency of only about 8%, resulting in a large amount of unconverted waste heat being emitted into the atmosphere during the non-heating season, causing energy waste. This invention stores the waste heat emitted during the Organic Rankine Cycle power generation process in the soil through buried pipes, turning waste into treasure. This not only avoids thermal pollution but also enables cross-seasonal utilization of solar energy (cross-seasonal energy storage), significantly improving the overall utilization rate of solar energy during the non-heating season.

[0035] 3. This invention couples the buried pipe, solar collector, and evaporator together during the heating season (heating mode); solving the problem of insufficient low-temperature heat source supply and poor operating conditions of a single solar heat pump system in winter (especially at night or on cloudy days). By utilizing the heat energy stored in the soil during summer and the solar energy in winter as a combined heat source, it overcomes the shortcomings of a single solar heat pump and significantly improves the heating capacity and operating efficiency of the heat pump system in winter.

[0036] 4. The hot water storage tank is equipped with a flow divider and automatic water replenishment; this solves the problem of heat loss caused by the mixing of hot and cold water in the tank; the flow divider promotes water temperature stratification, reduces heat loss caused by the mixing of hot and cold water, and at the same time plays a buffer role in the system, improving the overall stability and safety of operation.

[0037] 5. The combination of sensor networks and online simulation platforms solves the problem of soil thermal imbalance caused by the mismatch between heat extraction and heat storage in geothermal systems during long-term operation, which ultimately leads to the failure of buried pipes. Through online simulation and real-time monitoring, the joint control of valves and power equipment is improved, effectively predicting and preventing buried pipe failure and extending the system life.

[0038] 6. This invention's system, by deeply utilizing solar energy, reduces the proportion of heating systems relying on fossil fuel combustion in both urban and rural areas, thereby lowering carbon emissions. Furthermore, the system's dual-mode thermoelectric output provides a new approach for selecting energy equipment for rural self-use and for constructing distributed energy stations in cities. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the integrated system of the present invention. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0041] Example 1

[0042] See Figure 1 An integrated solar-powered cross-seasonal soil energy storage heating and power generation system based on an expansion compressor includes an expansion compressor 1, a permanent magnet motor 2, an evaporator 3, a condenser 4, an expansion valve 5, a working fluid pump 6, a solar collector 7, a hot water storage tank 8, a buried pipe 9, and a user terminal 10; it also includes valve ah and circulation pumps I-IV.

[0043] The integrated system's piping is divided into refrigerant common piping A, heating season open piping B, non-heating season open piping C, and solar collector piping D; among which:

[0044] The refrigerant common line A includes a condenser 4, an expansion compressor 1, and an evaporator 3 connected in sequence.

[0045] During the heating season, the start-up pipeline B includes an expansion compressor 1 and a permanent magnet motor 2 connected to each other, as well as a condenser 4, an expansion valve 5 and an evaporator 3 connected in sequence. The evaporator 3 is connected to the underground pipe 9 through two pipelines, and the condenser 4 is connected to the user terminal 10 through two pipelines.

[0046] During the non-heating season, the opening pipeline C includes an expansion compressor 1, a permanent magnet motor 2, and a user terminal 10 connected in sequence. It also includes a condenser 4, a working fluid pump 6, and an evaporator 3 connected in sequence. The condenser 4 is connected to the underground pipe 9 through two pipelines.

[0047] The solar collector piping D includes an evaporator 3, a hot water storage tank 8, and a solar collector 7 connected in sequence. The water in the hot water storage tank 8 will stratify due to density differences caused by temperature variations. This reduces heat loss caused by the mixing of hot and cold water. Therefore, devices such as baffles are installed in the hot water storage tank to further promote this stratification, reduce heat loss, and improve system operating efficiency.

[0048] The system operates in two modes throughout the year: heating and power generation. In heating mode, the system includes: an evaporator 3 for heat exchange between liquid refrigerant and a heat source; an expansion compressor 1 for compressing low-temperature gaseous refrigerant; a permanent magnet motor 2 to power the expansion compressor; a condenser 4 for heat exchange between high-temperature gaseous refrigerant and user return water; an expansion valve 5 to maintain circulation pressure balance by causing a pressure drop in the condensed liquid refrigerant; a solar collector 7 for collecting solar energy and converting it into heat energy; a hot water tank 8 to maintain system stability and improve system regulation; buried pipes 9 for transporting heat energy stored in the soil during the non-heating season; a user terminal 10 for absorbing solar energy in the form of heating; a common refrigerant pipeline A, a heating season open pipeline B, and a solar collector pipeline D for transporting system refrigerant and circulating water; circulation pumps I, II, and III to overcome pressure drops in pipelines and equipment and maintain system circulation; and control valves a, b, c, d, e, and g for pipeline control and mode switching.

[0049] In heating mode, the solar collector 7 converts solar energy into heat energy, raising the temperature of the circulating water in the collector. After passing through the hot water storage tank 8, the water flows into the evaporator 3. At the same time, the circulating water in the buried pipe 9 carries out the heat stored in the soil during the non-heating season and flows into the evaporator 3. The hot water from the solar collector 7 and the hot water from the buried pipe 9 exchange heat with the low-temperature liquid refrigerant in the evaporator. The liquid refrigerant absorbs heat and begins to evaporate. The low-temperature gaseous refrigerant produced by evaporation is compressed into a high-temperature gaseous refrigerant by the expansion compressor 1 and flows into the condenser 4. The high-temperature gaseous refrigerant exchanges heat with the heating return water at the user end 10 and then condenses. After exchanging heat with the return water at the user end 10, the temperature rises and it flows into the user's heating network. The high-temperature liquid refrigerant produced by condensation flows through the expansion valve 5, causing a pressure drop and a decrease in temperature, before flowing back into the evaporator 3. This completes one heat pump heating cycle based on the reverse Carnot cycle.

[0050] In power generation mode, the system includes: an evaporator 3 for heat exchange between liquid refrigerant and a heat source; an expansion compressor 1 for work done by the expansion of gaseous refrigerant; a permanent magnet motor 2 for converting the mechanical energy output by the expansion compressor 1 into electrical energy; a condenser 4 for heat exchange between gaseous refrigerant and circulating water in underground pipes; a solar collector 7 for collecting solar energy and converting it into thermal energy; a hot water tank 8 for maintaining stable system operation and improving system regulation capabilities; an underground pipe 5 for transporting and storing residual heat after power generation in the soil; a working fluid pump 6 for pumping the condensed liquid refrigerant back to the evaporator 3; a user terminal 10 for absorbing solar energy in the form of electricity; a common refrigerant pipeline A, an open pipeline C during the non-heating season, and a solar collector pipeline D for transporting system refrigerant and circulating water; circulation pumps I, III, and IV for overcoming pressure drops generated by pipelines and equipment and maintaining system circulation; and control valves a, b, c, d, f, and h for pipeline control and mode switching.

[0051] In power generation mode, the solar collector 7 converts solar energy into heat energy, raising the temperature of the circulating water in the collector. The water then flows through the hot water storage tank 8 into the evaporator 3. The hot water from the solar collector 7 exchanges heat with the low-temperature liquid refrigerant in the evaporator. The liquid refrigerant absorbs heat and begins to evaporate. The continuously generated gaseous refrigerant increases the pressure inside the evaporator, performing work on the expansion compressor 1. The permanent magnet motor 2 converts the expansion compressor 1 into electrical energy, which is then transmitted to the user end 10. The gaseous refrigerant, after performing work, flows into the condenser 4 and exchanges heat with the circulating water in the buried pipe 7. The heated hot water then exchanges heat with the soil, storing the heat that was not converted into electrical energy in the organic Rankine cycle. The gaseous refrigerant condenses after heat exchange, and the resulting liquid refrigerant is pumped back to the evaporator 3 by the working fluid pump. This completes one low-temperature power generation cycle based on the organic Rankine cycle. The refrigerant used in this embodiment is an organic refrigerant, and its boiling point needs to meet the thermodynamic requirements of both the heating and power generation modes. Specifically, R245FA can be selected.

[0052] Preferably, in order to achieve optimal operation control of the entire system through real-time monitoring of system operation, parameters such as temperature, flow rate, and pressure of important system nodes can be collected, transmitted, and analyzed in real time, such as the outlet temperature of the solar collector, the lower outlet temperature of the hot water storage tank, the supply water temperature of the buried pipe, the return water temperature of the buried pipe, the heating temperature at the user end, the return water temperature at the user end, the pressure inside the evaporator, and the pressure inside the condenser.

[0053] Preferably, to ensure the safe operation of the system and extend its service life, the soil temperature near the buried pipe can be monitored. This prevents significant differences in soil heat extraction and storage capacity caused by improper operation strategies or design and construction, which could lead to soil thermal imbalance, a continuous decline in system heat extraction or storage efficiency, and ultimately, pipe failure. Temperature sensors can be installed near the buried pipe to monitor soil temperature in real time, and the occurrence of soil thermal imbalance can be determined based on the annual soil temperature variation trend.

[0054] Specifically: When the annual variation in soil temperature exceeds 2℃, the system can be considered to have experienced initial thermal imbalance, requiring adjustments based on the specific circumstances.

[0055] If the soil temperature gradually rises, it indicates that the heat stored in the system during the non-heating season is greater than the heat extracted during the heating season. The operating power of the system should be increased during the heating season.

[0056] If the soil temperature gradually decreases, it indicates that the heat stored in the system during the non-heating season is less than the heat extracted during the heating season. The operating power of the system should be reduced during the heating season.

[0057] Furthermore, while using sensors to monitor the operating status of the integrated system, valves can be installed at key points to adjust the system in conjunction with a variable frequency power unit based on the system's operating status. Additionally, the installation of valves facilitates system installation, periodic maintenance, and replacement.

[0058] Preferably, the mode switching in the system is mainly achieved through switching valves. The mode switching is also the switching of heat users. During the switching, it is necessary to systematically adjust the control valves in each cycle to achieve the rematch of the entire system with heat users when switching modes.

[0059] Preferably, by recording system operating parameters under different modes over a long period, an integrated system operating parameter dataset is formed. This dataset can then be used to establish an online simulation platform for the integrated system through numerical simulation. The simulation platform can be used to refine the joint control strategy for valves and power equipment during system operation, improve the joint regulation scheme of valves and power devices, and further enhance the system's operating efficiency and dynamic adjustment strategy in the event of soil thermal imbalance.

[0060] The integrated compressor can be implemented using the technical solutions disclosed in the patent title: An integrated compressor-expansion machine (202411471953.6) or Integrated compressor-expansion machine, heat exchange system and power generation system (202211026156.8).

[0061] Example 2

[0062] Based on the same inventive concept, this application also provides an operation method for a solar cross-seasonal soil energy storage heating and power generation integrated system based on an expansion compressor. The operation method includes operation steps in the heating mode during the heating season and operation steps in the power generation mode during the non-heating season.

[0063] During the heating season, the following steps shall be taken to operate the heating mode:

[0064] Step S11: The solar collector 7 converts solar energy into thermal energy to heat the circulating water in the collector. The hot water flows into the evaporator 3 through the hot water storage tank 8. At the same time, the circulating water in the buried pipe 9 carries out the heat stored in the soil during the non-heating season and flows into the evaporator 3.

[0065] Step S12: The hot water from the solar collector 7 and the hot water from the buried pipe 9 together serve as a low-temperature heat source, exchanging heat with the low-temperature liquid refrigerant in the evaporator 3, so that the liquid refrigerant absorbs heat and evaporates into a low-temperature gaseous refrigerant.

[0066] Step S13: The low-temperature gaseous refrigerant is compressed into a high-temperature gaseous refrigerant by the expansion compressor 1 and then flows into the condenser 4;

[0067] Step S14: The high-temperature gaseous refrigerant exchanges heat with the heating return water of user 10 in the condenser 4 and condenses. After the user's heating return water is heated, it flows into the user's heating network.

[0068] Step S15: The high-temperature liquid refrigerant generated by condensation flows through the expansion valve 5, causing a pressure drop and a decrease in temperature, before flowing back into the evaporator 3, completing the heat pump heating cycle based on the reverse Carnot cycle.

[0069] During the non-heating season, the following steps should be followed to operate in power generation mode:

[0070] Step S21: The solar collector 7 converts solar energy into thermal energy, and the hot water flows into the evaporator 3 through the hot water storage tank 8;

[0071] Step S22: The hot water in the solar collector 7 exchanges heat with the low-temperature liquid refrigerant in the evaporator 3. The liquid refrigerant absorbs heat and evaporates, producing gaseous refrigerant and increasing the pressure inside the evaporator 3.

[0072] Step S23: The gaseous refrigerant expands the expansion compressor 1, which drives the permanent magnet motor 2 to convert mechanical energy into electrical energy and deliver it to the user 10.

[0073] Step S24: The gaseous refrigerant after doing work flows into the condenser 4 and exchanges heat with the circulating water in the underground pipe 9 to condense; the circulating water in the condenser 4, after being heated, exchanges heat with the soil through the underground pipe 9, storing the heat that has not been converted into electrical energy in the soil.

[0074] Step S25: The liquid refrigerant generated by condensation is pumped back to the evaporator 3 by the working fluid pump 6, completing the low-temperature power generation cycle based on the organic Rankine cycle.

[0075] Preferably, the integrated system switches the operating mode of the expansion compressor 1 by adjusting the power supply status of the permanent magnet motor 2: when the integrated system switches to heating mode, it supplies power to the permanent magnet motor 2, which drives the bearing of the expansion compressor 1 to rotate, making it operate as a compressor; when the integrated system switches to power generation mode, it stops supplying power to the permanent magnet motor 2, and the gaseous refrigerant generated in the evaporator 3 drives the bearing of the expansion compressor 1 to rotate, making it operate as an expander and drive the permanent magnet motor 2 to generate electricity.

[0076] Preferably, the operation method further includes system monitoring and control steps: real-time acquisition of the outlet temperature of the solar collector 7, the lower outlet temperature of the hot water storage tank 8, the supply and return water temperatures of the buried pipe 9, the supply and return water temperatures of the user 10, and the pressure parameters in the evaporator 3 and condenser 4; real-time monitoring of soil temperature using a temperature sensor installed near the buried pipe 9, and determination of soil thermal imbalance based on the annual soil temperature change trend; recording system operation parameter datasets under different modes using an online simulation platform, and combining the soil thermal imbalance determination results, dynamically adjusting the system operation in conjunction with the variable frequency power unit and various control valves.

[0077] The above embodiments can be applied to rural solar clean heating stations and urban distributed energy stations to improve the utilization efficiency of solar energy, reduce fossil energy consumption, alleviate the pressure on urban heating networks and power grids, and provide new technical support for urban energy transformation and urban planning and construction.

[0078] The aforementioned expansion compressor, permanent magnet motor, evaporator, condenser, expansion valve, working fluid pump, solar collector, hot water storage tank, underground pipe, valve, and circulating pump can use existing devices and materials; or they can be constructed using existing devices and materials and conventional technical means.

[0079] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A solar-powered, cross-seasonal soil energy storage system for heating and power generation based on an expansion compressor, characterized in that, The system includes an expansion compressor (1), a permanent magnet motor (2), an evaporator (3), a condenser (4), an expansion valve (5), a working fluid pump (6), a solar collector (7), and a buried pipe (9); the piping of the integrated system is divided into a refrigerant common pipeline A, a heating season open pipeline B, a non-heating season open pipeline C, and a solar collector pipeline D. In the non-heating season, the system is in power generation mode: the circulation pipeline consists of the refrigerant common pipeline A, the non-heating season open pipeline C, and the solar collector pipeline D, and the working fluid pump (6) is turned on; the heat generated by the solar collector (7) enters the evaporator (3) to evaporate the liquid refrigerant, and the gaseous refrigerant drives the expansion compressor (1), which operates as an expander, to do work and drive the permanent magnet motor (2) to generate electricity; the gaseous refrigerant after doing work enters the condenser (4) to exchange heat with the circulating water in the buried pipe (9) and condenses, and the heat that is not converted into electrical energy is stored in the soil through the buried pipe (9); the condensed liquid refrigerant is pumped back to the evaporator (3) by the working fluid pump (6). During the heating season, under heating mode: the circulation pipeline consists of the refrigerant common pipeline A, the heating season open pipeline B, and the solar collector pipeline D; the permanent magnet motor (2) is energized and drives the expansion compressor (1) which operates as a compressor; the heat generated by the solar collector (7) and the soil heat extracted by the buried pipe (9) together enter the evaporator (3) as a low-temperature heat source, causing the liquid refrigerant to evaporate; the gaseous refrigerant is compressed into a high-temperature gaseous refrigerant by the expansion compressor (1) and then enters the condenser (4), where it exchanges heat with the heating network at the user end (10) and condenses. The condensed liquid refrigerant is depressurized by the expansion valve (5) and then flows into the evaporator (3).

2. The integrated system according to claim 1, characterized in that, It also includes a hot water storage tank (8), the solar collector (7) is connected to the hot water storage tank (8), and the hot water storage tank (8) is set between the solar collector (7) and the evaporator (3) as a buffer.

3. The integrated system according to claim 2, characterized in that, The hot water storage tank (8) is equipped with a diversion baffle to cause the water to stratify based on density difference; and the hot water storage tank (8) is equipped with a water supply port connected to the municipal water network.

4. The integrated system according to claim 1, characterized in that, The system is equipped with sensors distributed at each node to collect in real time the outlet temperature of the solar collector, the outlet temperature at the bottom of the hot water storage tank, the supply / return water temperature of the buried pipe, the heating temperature at the user end, the return water temperature at the user end, the pressure inside the evaporator, and the pressure inside the condenser; and a temperature sensor is installed near the buried pipe (9) to monitor soil temperature changes to prevent soil thermal imbalance.

5. The integrated system according to claim 1, characterized in that, Each pipeline is equipped with several control valves and circulation pumps. The switching between the refrigerant common pipeline A, the heating season open pipeline B, and the non-heating season open pipeline C is achieved by shutting down each control valve.

6. The integrated system according to claim 1, characterized in that, The refrigerant common pipeline A includes a condenser (4), an expansion compressor (1), and an evaporator (3) connected in sequence.

7. The integrated system according to claim 1, characterized in that, The heating season start-up pipeline B includes an expansion compressor (1) and a permanent magnet motor (2) connected to each other, as well as a condenser (4), an expansion valve (5) and an evaporator (3) connected in sequence. The evaporator (3) is connected to the underground pipe (9) through two pipelines, and the condenser (4) is connected to the user end (10) through two pipelines.

8. The integrated system according to claim 1, characterized in that, The non-heating season opening pipeline C includes an expansion compressor (1), a permanent magnet motor (2) and a user terminal (10) connected in sequence, and also includes a condenser (4), a working fluid pump (6) and an evaporator (3) connected in sequence. The condenser (4) is connected to the underground pipe (9) through two pipelines.

9. The integrated system according to claim 1, characterized in that, The solar collector pipeline D includes an evaporator (3), a hot water storage tank (8), and a solar collector (7) connected in sequence.

10. An operation method for a solar-powered interseasonal soil energy storage heating and power generation integrated system based on any one of claims 1-9, characterized in that, The operation method includes the operation steps of the heating mode during the heating season and the operation steps of the power generation mode during the non-heating season; During the heating season, the following steps shall be taken to operate the heating mode: In step S11, the solar collector (7) converts solar energy into thermal energy to heat the circulating water in the collector. The hot water flows into the evaporator (3) through the hot water storage tank (8). At the same time, the circulating water in the underground pipe (9) carries out the heat stored in the soil during the non-heating season and flows into the evaporator (3). In step S12, the hot water from the solar collector (7) and the hot water from the buried pipe (9) are used together as a low-temperature heat source to exchange heat with the low-temperature liquid refrigerant in the evaporator (3), so that the liquid refrigerant absorbs heat and evaporates into a low-temperature gaseous refrigerant. In step S13, the low-temperature gaseous refrigerant is compressed into a high-temperature gaseous refrigerant by the expansion compressor (1) and then flows into the condenser (4). In step S14, the high-temperature gaseous refrigerant exchanges heat with the heating return water of the user end (10) in the condenser (4) and condenses. After the user's heating return water is heated, it flows into the user's heating network. In step S15, the high-temperature liquid refrigerant generated by condensation flows through the expansion valve (5) to generate a pressure drop and a decrease in temperature, and then flows back into the evaporator (3) to complete the heat pump heating cycle based on the reverse Carnot cycle. During the non-heating season, the following steps will be taken to operate in power generation mode: In step S21, the solar collector (7) converts solar energy into thermal energy, and the hot water flows into the evaporator (3) through the hot water storage tank (8). In step S22, the hot water in the solar collector (7) exchanges heat with the low-temperature liquid refrigerant in the evaporator (3). The liquid refrigerant absorbs heat and evaporates, generating gaseous refrigerant and increasing the pressure inside the evaporator (3). In step S23, the gaseous refrigerant expands and does work on the expansion compressor (1), driving the permanent magnet motor (2) to convert mechanical energy into electrical energy and deliver it to the user end (10). In step S24, the gaseous refrigerant after doing work flows into the condenser (4) and condenses by exchanging heat with the circulating water in the underground pipe (9); the circulating water in the condenser (4) after being heated exchanges heat with the soil through the underground pipe (9) and stores the heat that has not been converted into electrical energy in the soil. In step S25, the liquid refrigerant generated by condensation is pumped back to the evaporator (3) by the working fluid pump (6), thus completing the low-temperature power generation cycle based on the organic Rankine cycle; The operation method also includes system monitoring and control steps: real-time acquisition of the outlet temperature of the solar collector (7), the lower outlet temperature of the hot water storage tank (8), the supply and return water temperatures of the buried pipe (9), the heating temperature at the user end, the return water temperature at the user end, and the pressure parameters in the evaporator (3) and condenser (4); real-time monitoring of soil temperature through temperature sensors set near the buried pipe (9), and judgment of whether soil thermal imbalance has occurred based on the annual soil temperature change trend; recording system operation parameter datasets under different modes using an online simulation platform, and combining the judgment results of the soil thermal imbalance, dynamically adjusting the system operation in conjunction with the variable frequency power unit and various control valves.

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