Dual effect gravity heat pipe ground source heat pump system and method for heating / cooling

Abstract

The application discloses a double-effect gravity heat pipe type ground source heat pump system and method for realizing heating / cooling, which comprises a ground heat pump unit and a gravity heat pipe. The ground heat pump unit comprises a heat pump compressor, a four-way valve, an output end heat exchanger and a buffer tank. The inlet and outlet of the heat pump compressor are connected with upper and lower two interfaces of the four-way valve respectively. One end of a heat exchange pipeline of the output end heat exchanger is connected to a right interface of the four-way valve. The other end of the heat exchange pipeline of the output end heat exchanger is connected to the buffer tank. The buffer tank is connected to the lower interface of the four-way valve through a pipeline. The gravity heat pipe comprises a gravity heat pipe outer pipe. A plurality of liquid storage grooves are arranged in the wall of the gravity heat pipe outer pipe in a vertical direction. Adjacent two liquid storage grooves are connected through a liquid level control pipe. The liquid storage groove at the top is connected to the buffer tank through a liquid injection pipe. A liquid return pipe extending upwards is arranged at the bottom liquid pool of the gravity heat pipe. The liquid return pipe is connected to the buffer tank. The system works in a cooling mode and a heating mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geothermal energy development, in particular to a double-effect gravity heat pipe type ground source heat pump system and method for realizing heating / cooling. BACKGROUND

[0002] In most areas of China, the rock temperature at 10-100m underground is stable, and is about 20℃ all the year round, with a very small seasonal variation. The ground source heat pump system can use the rock body in the constant temperature zone as the cold source of the heat pump in summer, and as the heat source of the heat pump in winter, compared with the conventional air source heat pump, the power consumption in the system operation process can be significantly reduced.

[0003] The conventional ground source heat pump system needs to drill a geothermal well with a depth of 80-200m, and inject pipes and return pipes are arranged in the geothermal well, then water is pumped through the inject pipes, return pipes and heat pump heat exchangers in turn, and returns to the injection pipe for circulation, so as to use the underground constant temperature layer to provide the cold source or heat source for the heat pump system.

[0004] The gravity heat pipe ground source heat pump system uses a gravity heat pipe to replace the inject pipes and return pipes arranged in the well. Then the heat pump working medium is injected into the gravity heat pipe, which can directly enter the heat pump compressor after being converted into gaseous working medium after absorbing heat. Compared with the conventional ground source heat pump system, the gravity heat pipe ground source heat pump system is equivalent to arranging the heat pump evaporator directly in the geothermal well, thereby reducing the first heat transfer loss and the circulating pump power consumption, and higher cooling and heating efficiency can be obtained.

[0005] However, the heat transfer of the gravity heat pipe is unidirectional, and can only realize the heat transfer from bottom to top, so it can only meet the operation condition of the ground source heat pump system in winter heating, and cannot be used for summer cooling. On the other hand, the system is in a single heating operation state for a long time, which will cause the soil temperature to gradually decrease due to insufficient heat compensation of the underground constant temperature layer, and thus the system heating capacity will decrease. The above problems seriously limit the wide promotion of the gravity heat pipe ground source heat pump system. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a double-effect gravity heat pipe type ground source heat pump system and method for realizing heating / cooling, which improves the structure of the gravity heat pipe to enable heat transfer from top to bottom, and designs a matching ground heat pump unit, so as to stably and efficiently realize the functions of "summer cooling and winter heating".

[0007] To achieve the above object, the present application can adopt the following technical solutions:

[0008] In a first aspect, the present application provides a double-effect gravity heat pipe type ground source heat pump system for realizing heating or / and cooling, which comprises:​

[0009] A ground heat pump unit includes a heat pump compressor, a four-way valve, an output heat exchanger, and a buffer tank. The inlet and outlet of the heat pump compressor are respectively connected to the upper and lower ports of the four-way valve. One end of a heat exchange pipe of the output heat exchanger is connected to the right port of the four-way valve, and the other end of the heat exchange pipe of the output heat exchanger is connected to the buffer tank. The buffer tank is connected to the lower port of the four-way valve through a pipe.

[0010] A gravity heat pipe includes an outer tube and multiple liquid storage tanks arranged vertically inside the wall of the outer tube. The upper and lower adjacent liquid storage tanks are connected by a liquid level control pipe. The top liquid storage tank is connected to a buffer tank through an injection pipe. The bottom liquid pool of the gravity heat pipe is provided with an upward-extending return pipe, which is connected to the buffer tank. The system operates in both cooling and heating modes.

[0011] In the dual-effect gravity heat pipe ground source heat pump system described above, the pipeline between the buffer tank and the lower interface of the four-way valve is equipped with a pressure relief valve; the heat exchange pipeline of the output heat exchanger connected to the buffer tank is equipped with a throttling valve; and at least one condensate drain valve is provided at the bottom of each of the liquid storage tanks.

[0012] In the dual-effect gravity heat pipe ground source heat pump system described above, the bottom of the return pipe is submerged below the liquid pool, and at least one bypass valve is provided on the return pipe located above the liquid pool.

[0013] In the dual-effect gravity heat pipe ground source heat pump system described above, the bottom of the gravity heat pipe is provided with a liquid level detector for detecting the water level of the liquid pool. The liquid level detector has two liquid level detection ports. The upper liquid level detection port is arranged at a height lower than the bypass valve, and the lower liquid level detection port is arranged at a height higher than the bottom of the return pipe.

[0014] In the dual-effect gravity heat pipe ground source heat pump system described above, a return valve is provided on one end of the return pipe connected to the buffer tank, and an injection valve is provided on one end of the injection pipe connected to the buffer tank.

[0015] In the dual-effect gravity heat pipe ground source heat pump system described above, the four-way valve, the drain valve, and the bypass valve are pressure-controlled automatic switching valves or electrically controlled valves; the working fluid is any one of distilled water, ammonia, carbon dioxide, refrigerant, or organic working fluid.

[0016] Secondly, the present invention also provides a dual-effect gravity heat pipe type ground source heating and cooling method, which utilizes the above-mentioned system and includes a first operating mode for cooling and a second operating mode for heating, wherein...

[0017] The first working mode includes: the gaseous working fluid is pressurized by the heat pump compressor and enters the gravity heat pipe from the top. It releases heat and condenses on the inner wall of the outer tube of the gravity heat pipe and flows to the bottom of the outer tube of the gravity heat pipe. Then it returns to the buffer tank located on the ground through the return pipe. After being depressurized by the throttling valve, it enters the heat exchanger at the output end to evaporate and absorb heat.

[0018] The second working mode includes: the liquid working fluid after exothermic condensation returns to the buffer tank through the throttling valve, then enters the gravity heat pipe through the injection pipe, and fills each level of the liquid storage tank from top to bottom and absorbs heat and evaporates, then flows upward into the heat pump compressor, and after compression, enters the condenser at the output end to condense and release heat.

[0019] In the dual-effect gravity heat pipe ground source heating and cooling method described above, the condensate drain valve is in the open state in the first working mode and in the closed state in the second working mode.

[0020] In the above-described dual-effect gravity heat pipe ground source heating and cooling method, further, in the first working mode, the pressure in the buffer tank is lower than the internal pressure of the gravity heat pipe by adjusting the opening of the pressure relief valve, thereby allowing the liquid working fluid at the bottom of the gravity heat pipe to enter the return pipe.

[0021] In the above-described dual-effect gravity heat pipe ground source heating and cooling method, when the liquid working fluid enters the return pipe, the bypass valve can be opened intermittently, so that the liquid working fluid flows into the buffer tank in the form of a plunger flow.

[0022] Compared with the prior art, the advantages of this invention are as follows:

[0023] 1. This invention uses gravity heat pipes instead of the single-phase working fluid heat exchange pipes of traditional ground source heat pumps to absorb geothermal energy. It eliminates the need for circulating water as a heat transfer medium, and removes the need for a water circulation system and a ground evaporator, thus reducing the heat exchange process during working fluid exchange. This avoids losses and also prevents the consumption of circulating pump power, resulting in higher cooling and heating efficiency.

[0024] 2. The dual-effect gravity heat pipe ground source heat pump system designed in this invention solves the problem that conventional gravity heat pipes can only achieve single-phase heat transfer "from bottom to top", enabling the gravity heat pipe ground source heat pump to "cool in summer and heat in winter", and also avoids the problem of long-term performance degradation of single-effect gravity heat pipes. While expanding the application scope of this technology, it also improves the stability of long-term operation.

[0025] 3. The dual-effect gravity heat pipe ground source heat pump system designed in this invention has a liquid-retaining valve inside, which makes the structure have variable characteristics. It can keep the inner wall dry in the "cooling" mode and keep the inner wall moist in the "heating" mode, thereby further improving the cooling / heating efficiency of the system.

[0026] 4. The dual-effect gravity heat pipe ground source heat pump system designed in this invention has a buffer tank in the ground heat pump unit, which enables the system to switch flexibly between cooling / heating conditions and improves its operational reliability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of a dual-effect gravity heat pipe ground source heat pump system for heating / cooling according to an embodiment of the present invention.

[0029] The components include: 1. Heat pump compressor; 2. Four-way valve; 3. Output heat exchanger; 4. Pressure relief valve; 5. Return valve; 6. Injection valve; 7. Throttling valve; 8. Buffer tank; 9. Gravity heat pipe outer tube; 10. Injection pipe; 11. Return pipe; 12. Storage tank; 13. Liquid level control pipe; 14. Drain valve; 15. Bypass valve; 16. Liquid level detector. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0031] Example:

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, in the embodiments of this invention are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0034] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] See Figure 1This invention provides a dual-effect gravity heat pipe ground source heat pump system for heating / cooling, which may include: a ground heat pump unit and a gravity heat pipe. The ground heat pump unit includes a heat pump compressor 1, a four-way valve 2, an output heat exchanger 3, and a buffer tank 8. The inlet and outlet of the heat pump compressor 1 are respectively connected to the upper and lower ports of the four-way valve 2. One end of a heat exchange pipe of the output heat exchanger 3 is connected to the right port of the four-way valve 2, and the other end of the heat exchange pipe of the output heat exchanger 3 is connected to the buffer tank 8. The gravity heat pipe is connected to the lower interface of the four-way valve 2 via a pipe; the gravity heat pipe includes an outer gravity heat pipe 9, and the inner wall of the outer gravity heat pipe 9 is provided with multiple liquid storage tanks 12 in the vertical direction. The upper and lower adjacent liquid storage tanks 12 are connected by a liquid level control pipe 13. The liquid storage tank 12 located at the top is connected to the buffer tank 8 through a liquid injection pipe 10. The bottom liquid pool of the gravity heat pipe is provided with an upwardly extending return pipe 11, which is connected to the buffer tank 8. The system operates in cooling mode and heating mode.

[0037] Specifically, this system can achieve the function of "cooling in summer and heating in winter": In the "cooling" mode, the gravity heat pipe will act as the condenser of the heat pump system. The gaseous working fluid is pressurized by the heat pump compressor 1 and enters the gravity heat pipe from the top. Then, it releases heat and condenses on the inner wall of the heat pipe and flows to the bottom of the heat pipe. Then, it returns to the buffer tank 8 located on the ground through the return pipe 11. After being depressurized by the throttling valve 7, it enters the heat exchanger to evaporate and absorb heat, thereby achieving the purpose of "cooling". In the "heating" mode, the liquid working fluid after releasing heat and condensing returns to the buffer tank 8 through the throttling valve 7. Then, it enters the gravity heat pipe through the injection pipe 10 and fills the various levels of liquid storage tanks 12 from top to bottom. The liquid working fluid in the liquid storage tanks 12 will continue to absorb heat and evaporate. Then, it flows upward into the heat pump compressor 1 located on the ground. After being compressed, it enters the heat exchanger to release heat and condense, thereby achieving the purpose of "heating". In this embodiment, a gravity heat pipe replaces the single-phase working fluid heat exchange pipeline of a traditional ground source heat pump for absorbing geothermal energy. It eliminates the need for circulating water as a heat transfer medium, as well as a water circulation system and a ground evaporator, thus reducing the heat exchange process during working fluid exchange. This invention not only avoids heat loss but also eliminates the energy consumption of the circulating pump, resulting in higher cooling and heating efficiency. Furthermore, the embodiments of this invention solve the problem that conventional gravity heat pipes can only achieve single-phase heat transfer "from bottom to top," enabling gravity heat pipe ground source heat pumps to provide both cooling in summer and heating in winter. It also avoids the long-term performance degradation problem of single-effect gravity heat pipes, expanding the application scope of this technology while improving long-term operational stability.

[0038] See you again Figure 1 , Figure 1A dual-effect gravity heat pipe ground source heat pump system for heating / cooling is demonstrated, comprising a ground heat pump unit and a gravity heat pipe. The ground heat pump unit includes a heat pump compressor 1, a four-way valve 2, an output heat exchanger 3, a pressure relief valve 4, a return valve 5, an injection valve 6, a throttling valve 7, and a buffer tank 8. The gravity heat pipe includes an outer gravity heat pipe 9, an injection pipe 10, a return pipe 11, and a multi-stage liquid storage tank 12.

[0039] The top steam outlet of the gravity heat pipe is connected to the inlet and outlet of the heat pump compressor 1 via a four-way valve 2. At the same time, the output heat exchanger 3 is also connected to the inlet and outlet of the heat pump compressor 1 via a four-way valve 2. The bottom of the buffer tank 8 is connected to the output heat exchanger 3 via a throttle valve 7, and the top of the buffer tank 8 is connected to the inlet of the heat pump compressor 1 via a pressure relief valve 4.

[0040] Furthermore, each storage tank 12 includes a liquid level control pipe 13 and a condensate drain valve 14 at the bottom of the tank. The condensate drain valve 14 is pressure-controlled; when the pressure is higher than P0, the condensate drain valve 14 opens. Meanwhile, the inner walls of the gravity heat pipes between each storage tank 12 that are not covered by liquid working fluid can be kept moist by arranging wicks.

[0041] Furthermore, the top of the injection pipe 10 is connected to the buffer tank 8 via the return valve 5, and the bottom of the injection pipe 10 is inserted into the topmost storage tank 12.

[0042] Furthermore, the top of the return pipe 11 is connected to the buffer tank 8 via the injection valve 6, and the bottom of the return pipe 11 is inserted below the bottom liquid pool of the gravity heat pipe. A bypass valve 15 is provided on the liquid pool, and the switch of the bypass valve 15 can be controlled from the ground.

[0043] In addition, a liquid level detector 16 is installed at the bottom of the gravity heat pipe, which includes two liquid level detection ports, an upper liquid level detection port and a lower liquid level detection port. The upper liquid level detection port is arranged at a height lower than the bypass valve 15, and the lower liquid level detection port is arranged at a height higher than the bottom of the return pipe 11.

[0044] In this embodiment, the ground heat pump unit is designed as follows: the inlet and outlet of the heat pump compressor 1 are connected to the heat exchanger and the gas channel at the top of the gravity heat pipe via a four-way valve 2, respectively, allowing switching between two working fluid flow directions: "top of gravity heat pipe → inlet of heat pump compressor 1 → outlet of heat pump compressor 1 → heat exchanger" and "heat exchanger → inlet of heat pump compressor 1 → outlet of heat pump compressor 1 → top of gravity heat pipe"; the buffer tank 8 is connected to the inlet of the heat pump compressor 1 via a connecting pipe, and the opening and closing of this pipe is controlled by a pressure relief valve 4; the buffer tank 8 is connected to the liquid injection pipe 10 and the liquid return pipe 11 of the gravity heat pipe, and the opening and closing of the two pipes are controlled by the liquid injection valve 6 and the liquid return valve 5, respectively; the buffer tank 8 is equipped with a real-time pressure and liquid level detection device, and the pressure and liquid level in the buffer tank 8 can be controlled by the opening and closing of the pressure relief valve 4, the liquid injection valve 6, and the liquid return valve 5, thereby enabling the system to operate continuously at a constant temperature under cooling / heating conditions.

[0045] The internal structure of the gravity heat pipe is designed as follows: the inner wall of the gravity heat pipe is provided with multi-stage annular liquid storage tanks 12. Each liquid storage tank 12 includes a condensate drain valve 14 and a liquid level control pipe 13. The condensate drain valve 14 can be controlled from the ground. The top of the liquid level control pipe 13 is slightly lower than the height of the liquid storage tank 12, and its bottom is inserted into the next level liquid storage tank 12. A liquid level sensor is provided at the bottom of the gravity heat pipe. During actual operation, the liquid level at the bottom of the pipe will be controlled within a certain range. The top of the injection pipe 10 is connected to the buffer tank 8, and its bottom is inserted into the topmost liquid storage tank 12. The top of the return pipe 11 is also connected to the buffer tank 8, and the bottom of the return pipe 11 is inserted below the bottom liquid level. A bypass valve 15 is also provided at the bottom of the return pipe 11. The port of the bypass valve 15 is located above the bottom liquid level and can be controlled from the ground.

[0046] Specifically, in the "heating" mode, the liquid working fluid flows from the injection port into the top storage tank 12. At this time, the condensate trap 14 in the storage tank 12 is closed, and the liquid working fluid flows from top to bottom through the level control pipe 13, keeping the inner wall of the heat pipe always "wet," thus significantly improving the heat absorption efficiency of the heat pipe. In the "cooling" mode, the gaseous working fluid releases heat and condenses on the inner wall of the gravity heat pipe. At this time, the condensate trap 14 in the storage tank 12 is open, and the liquid working fluid flows directly from the middle of the gravity heat pipe to the bottom of the heat pipe. There is no liquid accumulation in the storage tank 12, keeping the inside of the heat pipe always "dry," thus significantly improving the heat release efficiency of the heat pipe.

[0047] Furthermore, in the "cooling" mode, the return pipe 11 is connected to the buffer tank 8, and the buffer tank 8 controls the opening of the pressure relief valve 4 to keep its pressure lower than that inside the gravity heat pipe. At this time, the liquid working fluid will flow upward from the return pipe 11. However, when the static pressure of gravity in the return pipe 11 is balanced with the pressure difference between the heat pipe and the buffer tank 8, the working fluid will stop flowing upward. At this time, the bypass valve 15 at the bottom of the return pipe 11 can be opened intermittently to introduce the gaseous working fluid into the bottom of the return pipe 11, so that the liquid working fluid in the return pipe 11 flows upward in the form of a plunger flow and finally enters the buffer tank 8, thus realizing the reverse phase transfer of heat "from top to bottom". Therefore, this system can solve the problem that conventional gravity heat pipes can only realize the single-phase transfer of heat "from bottom to top", enabling the gravity heat pipe ground source heat pump to "cool in summer and heat in winter", and also avoids the problem of long-term performance degradation of single-effect gravity heat pipes. While expanding the application scope of this technology, it also improves the long-term operational stability.

[0048] In one preferred embodiment, in some embodiments, the return pipe 11 may also be placed outside the gravity heat pipe, with the bottom of the return pipe 11 connected to the bottom liquid pool of the gravity heat pipe and the top connected to the buffer tank 8 via the return valve 5.

[0049] This invention also provides a dual-effect gravity heat pipe ground source heating and cooling method, which utilizes the above-mentioned system and may specifically include the following steps:

[0050] 1) Determine a suitable well location through geological exploration and drill to the target depth.

[0051] 2) Based on the downhole temperature measurement data and the system design power, select the working fluid and estimate the working fluid flow rate. Determine the diameter of the injection pipe 10, return pipe 11, level control pipe 13 and drain valve 14, as well as the height of each level of storage tank 12, through calculation or experiment to ensure that the fluid working fluid flow path is unobstructed and that no liquid accumulation effect occurs.

[0052] Specifically, the liquid-wicking valve 14 may include, but is not limited to, pressure-controlled automatic on / off valves and electrically controlled valves, as well as other valves that can achieve the same function. The working fluid may include, but is not limited to, distilled water, ammonia, carbon dioxide, various refrigerants, and organic working fluids.

[0053] 3) Install the liquid level control pipe 13 and the liquid drain valve 14 on the liquid storage tank 12 according to the parameters selected in step 2), and weld the liquid storage tank 12 to the inner wall of the outer tube 9 of the gravity heat pipe.

[0054] 4) Install two liquid level detectors 16 on the bottom blind plate of the gravity heat pipe.

[0055] 5) Perform casing running-in operation, place the processed gravity heat pipe outer tube 9 into the well, and inject mud between the outer tube and the wellbore for cementing and filling the gap between the outer tube and the rock mass.

[0056] 6) Evacuate the system through the buffer tank 8, and then close the throttle valve 7.

[0057] 7) After being pressurized by the heat pump compressor 1, the gaseous working fluid enters the gravity heat pipe from the top, releases heat and condenses on the inner wall of the outer tube 9 of the gravity heat pipe and flows to the bottom of the outer tube 9 of the gravity heat pipe. Then it returns to the buffer tank 8 located on the ground through the return pipe 11, and then enters the output end heat exchanger 3 for evaporation and heat absorption after being depressurized by the throttling valve 7.

[0058] Specifically, in refrigeration mode, by controlling the four-way valve 2, the outlet of the heat pump compressor 1 is connected to the top pipe of the gravity heat pipe, and the inlet of the heat pump compressor 1 is connected to the output heat exchanger 3; the liquid injection valve 6 is closed and the liquid return valve 5 is opened; liquid working fluid is continuously injected through the charging port on the buffer tank 8, and the heat pump compressor 1 is started, so that the internal pressure of the gravity heat pipe is higher than the opening pressure P0 of the condensate drain valve 14. At this time, the condensate drain valve 14 is closed, and the gaseous working fluid releases heat and condenses on the inner wall of the heat pipe and then flows directly to the bottom of the gravity heat pipe through the condensate drain valve 14. When the liquid level sensor detects that the liquid level is between the upper and lower liquid level monitoring points, the charging of liquid working fluid is stopped; the opening degree of the pressure relief valve 4 and the opening frequency and time of the bypass valve 15 are adjusted to control the fluctuation range of the liquid level in the buffer tank 8; the liquid working fluid in the buffer tank 8 will continuously flow into the output heat exchanger 3 through the expansion valve to absorb heat and evaporate, thereby achieving the purpose of refrigeration. It should be understood that the four-way valve 2 may include, but is not limited to, an integrated electrically controlled four-way valve 2, or other valve combinations that can achieve the same pipeline switching function; the bypass valve 15 may include, but is not limited to, pressure-controlled automatic switching valves and electrically controlled valves, as well as other valves that can achieve the same function.

[0059] 8) The liquid working fluid after exothermic condensation returns to the buffer tank 8 through the throttle valve 7, and then enters the gravity heat pipe through the liquid injection pipe 10. It fills the liquid storage tanks 12 from top to bottom and absorbs heat and evaporates. Then it flows upward into the heat pump compressor 1, and after compression, it enters the condenser at the output end to condense and release heat.

[0060] Specifically, under heating conditions, by controlling the four-way valve 2, the inlet of the heat pump compressor 1 is connected to the top pipe of the gravity heat pipe, and the outlet of the heat pump compressor 1 is connected to the output heat exchanger 3; the liquid injection valve 6 is opened, and the return valve 5 and the pressure relief valve 4 are closed; liquid working fluid is continuously injected through the charging port on the buffer tank 8, and the heat pump compressor 1 is started, so that the internal pressure of the gravity heat pipe is lower than the opening pressure P0 of the condensate drain valve 14. At this time, the condensate drain valve 14 is in the closed state, and the liquid working fluid in the buffer tank 8 flows through... The liquid flows through the injection pipe 10 to the top storage tank 12, and then through the level control pipe 13 from top to bottom through each storage tank 12 until the level sensor detects that the liquid level is between the upper and lower level monitoring points, at which point the liquid working fluid is stopped being injected. After the liquid working fluid absorbs heat and evaporates in the inner wall of the gravity heat pipe, it flows from the top of the heat pipe into the heat pump compressor 1. After being pressurized and heated, it flows to the output end heat exchanger 3 to condense and release heat. Then it flows through the expansion valve into the buffer tank 8 for circulation, thereby achieving the purpose of heating.

[0061] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0062] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A dual-effect gravity heat pipe ground source heat pump system for providing heating and / or cooling, characterized in that, include: A ground heat pump unit includes a heat pump compressor, a four-way valve, an output heat exchanger, and a buffer tank. The inlet and outlet of the heat pump compressor are respectively connected to the upper and lower ports of the four-way valve. One end of a heat exchange pipe of the output heat exchanger is connected to the right port of the four-way valve, and the other end of the heat exchange pipe of the output heat exchanger is connected to the buffer tank. The buffer tank is connected to the lower port of the four-way valve through a pipe. A gravity heat pipe includes an outer tube, with multiple liquid storage tanks arranged vertically inside the wall of the outer tube. Adjacent liquid storage tanks are connected by a level control pipe. The top liquid storage tank is connected to a buffer tank via an injection pipe. The bottom liquid pool of the gravity heat pipe has an upward-extending return pipe connected to the buffer tank. A pressure relief valve is provided on the pipe between the buffer tank and the lower interface of the four-way valve. A throttling valve is provided at the end of the heat exchanger's heat exchange pipeline connected to the buffer tank. At least one condensate trap is provided at the bottom of each liquid storage tank. The system operates in cooling and heating modes. In cooling mode, the condensate trap is open; in heating mode, the condensate trap is closed.

2. The dual-effect gravity heat pipe ground source heat pump system according to claim 1, characterized in that, The bottom of the return pipe is submerged below the liquid pool, and at least one bypass valve is provided on the return pipe located above the liquid pool.

3. The dual-effect gravity heat pipe ground source heat pump system according to claim 1, characterized in that, The bottom of the gravity heat pipe is equipped with a liquid level detector for detecting the water level in the liquid pool. The liquid level detector has two liquid level detection ports. The upper liquid level detection port is arranged at a height lower than the bypass valve, and the lower liquid level detection port is arranged at a height higher than the bottom of the return pipe.

4. The dual-effect gravity heat pipe ground source heat pump system according to claim 1, characterized in that, A return valve is provided on one end of the return pipe connected to the buffer tank, and an injection valve is provided on one end of the injection pipe connected to the buffer tank.

5. The dual-effect gravity heat pipe ground source heat pump system according to claim 1, characterized in that, Four-way valves, drain valves, and bypass valves are pressure-controlled automatic on / off valves or electrically controlled valves; the working fluid can be any one of distilled water, ammonia, carbon dioxide, or organic working fluid.

6. A dual-effect gravity heat pipe ground source heating and cooling method, characterized in that, The system is used as described in any one of claims 1 to 5, including a first operating mode for a cooling mode and a second operating mode for a heating mode, wherein... The first working mode includes: the gaseous working fluid is pressurized by the heat pump compressor and enters the gravity heat pipe from the top. It releases heat and condenses on the inner wall of the outer tube of the gravity heat pipe and flows to the bottom of the outer tube of the gravity heat pipe. Then it returns to the buffer tank located on the ground through the return pipe. After being depressurized by the throttling valve, it enters the heat exchanger at the output end to evaporate and absorb heat. The second working mode includes: the liquid working fluid after exothermic condensation returns to the buffer tank through the throttling valve, then enters the gravity heat pipe through the injection pipe, and fills each level of the liquid storage tank from top to bottom and absorbs heat and evaporates, then flows upward into the heat pump compressor, and after compression, enters the condenser at the output end to condense and release heat.

7. The dual-effect gravity heat pipe ground source heating and cooling method according to claim 6, characterized in that, In the first working mode, the pressure in the buffer tank is lower than the internal pressure of the gravity heat pipe by adjusting the opening of the pressure relief valve, thereby allowing the liquid working fluid at the bottom of the gravity heat pipe to enter the return pipe.

8. The dual-effect gravity heat pipe ground source heating and cooling method according to claim 6, characterized in that, When the liquid working fluid enters the return pipe, the bypass valve is opened intermittently, allowing the liquid working fluid to flow into the buffer tank in the form of a plunger flow.

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