Frozen earth conservation experiment device based on renewable energy sources and heat pump

Abstract

The invention provides a frozen soil conservation experiment device based on renewable energy sources and a heat pump, and relates to the technical field of frozen soil conservation. The device comprises a power supply unit, a control unit, a heat pump system and a temperature detection unit, the power supply unit is electrically connected with the control unit and the heat pump system; the control unit is used for controlling the heat pump system and is electrically connected with the temperature detection unit; the heat pump system comprises a first exchange device, a second exchange device, a compression device, an expansion valve and a multi-way valve. The first exchange device, the expansion valve, the second exchange device, the multi-way valve and the compression device are sequentially connected to form a channel. The first exchange device and the second exchange device are internally used for containing fluid refrigerants. The device is simple and reasonable in structure, and is suitable for remote or non-power-grid-supported frozen earth areas and scientific research scenes. Through the combination of renewable energy sources and heat pump circulation, unattended and all-weather soil temperature regulation and control can be achieved, and an efficient, clean and sustainable technical means is provided for frozen soil conservation and experimental research.

Description

Technical Field

[0001] This invention relates to the field of permafrost conservation technology, and more specifically, to an experimental device for permafrost conservation based on renewable energy and a heat pump. Background Technology

[0002] With global warming, permafrost degradation has led to a series of ecological and environmental problems, urgently requiring innovation in permafrost conservation technologies and experimental facilities. Permafrost (or simply permafrost) refers to soil and rock layers whose underground temperature remains at or below 0°C for at least two years. It is an important component of alpine ecosystems, playing a crucial role in global carbon cycling, hydrological processes, and ecosystem stability. However, with global warming, permafrost is degrading extensively, particularly in the Qinghai-Tibet Plateau region. Permafrost degradation manifests as thickening of the active layer, reduction of permafrost area, thaw collapse, and expansion of thaw lakes. The large amount of organic carbon stored in permafrost decomposes rapidly during degradation, releasing greenhouse gases such as carbon dioxide and methane, forming a positive feedback loop of "warming-degradation-carbon release-warming again," posing a serious threat to the global climate system, ecological environment, and permafrost engineering infrastructure. Therefore, how to effectively protect permafrost ecosystems has become an important issue.

[0003] To protect permafrost, it is necessary to study how to cool permafrost to stabilize it, and to conduct scientific research on the impact of permafrost degradation using soil warming simulation experiments. However, a mature system for bidirectional control of soil temperature throughout the year in permafrost regions (which can both cool and conserve permafrost and meet the needs of warming experiments) is still lacking. For permafrost experimental devices, open-top heating chambers (such as CN 218545760 U) or electric heating wire devices (such as CN119729925A) are currently the main methods used. Regarding permafrost cooling, current methods mainly involve active cooling of permafrost regions through insulation, ventilation, and artificial refrigeration to maintain permafrost at low temperatures or in a frozen state, thus mitigating the negative impacts of atmospheric warming. Examples include application publication numbers CN 107254818 A and CN 107724377 A.

[0004] However, the main problems with the aforementioned publicly available technologies are: they primarily focus on unidirectional soil cooling or warming, lacking flexible soil temperature control functions, thus limiting their application scenarios; the cooling or warming devices have relatively low energy efficiency, resulting in low cooling or heating efficiency and difficulty in stable operation; the cooling or warming devices can only be deployed in a point-like manner, limiting the temperature control area; and they cannot control the temperature in situ in frozen soil experiments to simulate the severe freeze-thaw process, failing to meet scientific research needs. Especially in scenarios requiring controlled soil heating and cooling (such as frozen soil warming experiments and soil freeze-thaw experiments) or unattended cooling for frozen soil conservation, existing solutions are insufficient. Therefore, it is necessary to provide a novel soil temperature control device to meet the needs of related frozen soil conservation and scientific experiments. Summary of the Invention

[0005] The purpose of this invention is to provide an experimental device for permafrost conservation based on renewable energy and heat pumps, which addresses the shortcomings of existing technologies and solves the problems mentioned in the background.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] An experimental device for permafrost conservation based on renewable energy and heat pumps includes a power supply unit, a control unit, a heat pump system, and a temperature detection unit;

[0008] The power supply unit is electrically connected to the control unit and the heat pump system;

[0009] The control unit is used to control the heat pump system and is electrically connected to the temperature detection unit;

[0010] The heat pump system includes a first heat exchanger, a second heat exchanger, a compression unit, an expansion valve, and a multi-way valve. The first heat exchanger, the expansion valve, the second heat exchanger, the multi-way valve, and the compression unit are connected in sequence to form a circuit.

[0011] The first and second exchange units are used to hold fluid refrigerant.

[0012] Furthermore, the power supply unit includes a solar panel, a battery pack, and a charge / discharge controller, with the solar panel electrically connected to the battery pack via the charge / discharge controller.

[0013] Furthermore, the power supply unit also includes a wind turbine, which is electrically connected to the battery pack via a charge / discharge controller.

[0014] Furthermore, the control unit is electrically connected to the charge / discharge controller, and the control unit performs communication management of the charge / discharge controller.

[0015] Furthermore, both the first and second switching devices are composed of multiple metal tubes, which together form a passageway.

[0016] Preferably, the first and second switching devices are laid out in at least one of the following patterns: linear, ring-shaped, or planar.

[0017] Preferably, the refrigerant is R600a or R717.

[0018] Furthermore, the battery pack is a lithium-ion battery or a lithium iron phosphate battery.

[0019] Preferably, both the multi-way valve and the compression device are electrically connected to the charge-discharge controller, which is used to provide electrical energy to the multi-way valve and the compression device.

[0020] The present invention has at least the following advantages or beneficial effects:

[0021] 1. The permafrost conservation experimental device provided by this invention has a simple and reasonable structure, and is suitable for remote or grid-free permafrost areas and scientific research scenarios. By combining renewable energy with heat pump cycles, unattended, all-weather soil temperature control can be achieved, providing an efficient, clean, and sustainable technical means for permafrost conservation and experimental research.

[0022] 2. The heat pump system employs a reversible operating mode, with the first and second heat exchange units alternately serving as condensers and evaporators. This design ensures a moderate operating temperature difference for the refrigerant, improving cycle efficiency and reducing energy consumption. In cooling mode, it utilizes soil-air heat exchange for efficient cooling, thereby cooling or freezing the soil, effectively protecting permafrost or restoring areas of permafrost degradation. In warming mode, it utilizes air-soil heat exchange for efficient heating, raising the soil temperature, which can be used for permafrost warming experiments. Alternating warming / cooling models can also be designed to simulate severe freeze-thaw processes in soil freeze-thaw experiments.

[0023] 3. This invention uses solar panels and wind turbines as power sources, based on renewable energy, and is clean and environmentally friendly. The configuration of the charge / discharge controller and battery pack enables effective management and storage of electrical energy, ensuring stable power supply even without sunlight or wind, thus improving energy efficiency and enhancing power supply stability and reliability. Furthermore, the tilted installation of the solar panels not only generates electricity but also acts as a shading panel to reduce surface heat radiation input, improving the permafrost conservation effect during cooling operations.

[0024] 4. The control unit collects the internal soil temperature through the temperature detection unit and controls the start and stop of the heat pump system. It automatically switches modes and controls various components according to the preset temperature range, requiring no manual intervention. Precise temperature feedback and control ensure that the soil temperature is maintained within the required range, providing high control accuracy. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the structure of an experimental device for permafrost conservation based on renewable energy and heat pumps provided by the present invention;

[0027] Figure 2 This invention provides a schematic diagram of the refrigerant flow principle under the heating mode of the frozen soil conservation experimental device;

[0028] Figure 3 A schematic diagram illustrating the refrigerant flow principle under the cooling operation mode of the experimental device for permafrost conservation provided by this invention.

[0029] Icons: 100, Power supply unit; 101, Solar panel; 103, Battery pack; 105, Charge / discharge controller; 107, Wind turbine; 200, Control unit; 300, Heat pump system; 310, First exchange unit; 330, Second exchange unit; 350, Compression unit; 370, Expansion valve; 390, Multi-way valve; 400, Temperature detection unit. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Please refer to Figures 1 to 3 As shown, an experimental device for permafrost conservation based on renewable energy and a heat pump includes a power supply unit 100, a control unit 200, a heat pump system 300, and a temperature detection unit 400. The power supply unit 100 is electrically connected to both the control unit 200 and the heat pump system 300, providing electrical energy to ensure their stable operation. The control unit 200 controls the start / stop and mode switching of the heat pump system 300. Furthermore, the control unit 200 is electrically connected to the temperature detection unit 400.

[0032] Specifically, in this technical solution, the control unit 200 is a PLC controller with a human-machine interface; the temperature detection unit 400 is an existing temperature sensor powered by a parasitic power source, drawing energy from the control system via a signal line. In actual use, operators can replace it with a temperature sensor powered by an external power source, for example, by having the power supply unit 100 supply power to the temperature detection unit 400. The temperature detection unit 400 is buried in the soil, enabling it to collect real-time soil temperature data and transmit the collected temperature data to the control unit 200.

[0033] The heat pump system 300 includes a first exchange unit 310, a second exchange unit 330, a compression unit 350, an expansion valve 370, and a multi-way valve 390. The first exchange unit 310, expansion valve 370, second exchange unit 330, multi-way valve 390, and compression unit 350 are sequentially connected to form a passage. The first exchange unit 310 and second exchange unit 330 are used to hold fluid refrigerant, which can flow in the passage under the action of the compression unit 350. In this embodiment, the refrigerant is R600a or R717. The compression unit 350 is a conventional compressor; the multi-way valve 390 is an electronic multi-way valve, electrically connected to the control unit 200. The control unit 200 can control the multi-way valve 390 to change the flow direction of the refrigerant within the heat pump system 300, thereby changing the operating mode of the heat pump system 300.

[0034] When using this device, operators first need to inject an appropriate amount of refrigerant into the first exchange unit 310 and the second exchange unit 330, and then bury the first exchange unit 310 and the temperature detection unit 400 in the soil, while the second exchange unit 330 is exposed to the air. The device is then operated through the interactive interface of the control unit 200. The temperature data collected in real time by the temperature detection unit 400 is transmitted to the control unit 200, which automatically adjusts the cooling or heating intensity based on the feedback from the temperature detection unit 400, thereby controlling the soil temperature. Specifically:

[0035] In cooling mode, the first exchange unit 310 operates as an evaporator, and the second exchange unit 330 operates as a condenser. At this time, the low-temperature, low-pressure liquid refrigerant absorbs heat from the soil and evaporates in the first exchange unit 310. The compression unit 350 compresses the evaporated refrigerant gas into a high-temperature, high-pressure gas, which is then guided to the second exchange unit 330 via the multi-way valve 390. The high-temperature, high-pressure refrigerant releases heat to the air and condenses into a liquid in the second exchange unit 330. Then, the refrigerant is throttled and cooled by the expansion valve 370, returning to the first exchange unit 310 to complete one cycle. During this repeated cycle, the underground soil continuously releases heat into the refrigerant, thereby cooling the soil. When the soil temperature is higher than the preset temperature, the control unit 200 controls the compression unit 350 to increase its operating power to increase the cooling intensity; when the soil temperature is lower than the preset temperature, the control unit 200 controls the compression unit 350 to reduce its operating power to save electricity.

[0036] In the heating mode, the second exchange unit 330 operates as an evaporator, and the first exchange unit 310 operates as a condenser. At this time, the refrigerant first comes into contact with the air in the second exchange unit 330 and absorbs heat before evaporating. The compressor 350 compresses the heat-absorbing refrigerant into a high-temperature, high-pressure gas and sends it to the first exchange unit 310. In the first exchange unit 310, the high-temperature, high-pressure refrigerant releases heat to the soil and condenses into a liquid. Then, the liquid refrigerant is throttled and cooled through the expansion valve 370 and returns to the second exchange unit 330 for the next cycle. This process repeats continuously, with the surface air continuously transferring heat to the underground soil, thereby raising the soil temperature. When the soil temperature is higher than the preset temperature, the control unit 200 controls the compressor 350 to reduce its operating power to save electricity; when the soil temperature is lower than the preset temperature, the control unit 200 controls the compressor 350 to increase its operating power to increase the cooling intensity.

[0037] In addition, the control unit 200 can also switch the multi-way valve 390 to change the direction of refrigerant flow based on the actual monitored soil temperature and the set threshold, automatically switching between cooling and heating modes without manual intervention, so as to achieve automatic constant temperature control of the soil temperature within the target range.

[0038] Please refer to this again. Figure 1 The power supply unit 100 includes a solar panel 101, a battery pack 103, and a charge / discharge controller 105. The solar panel 101 is electrically connected to the battery pack 103 through the charge / discharge controller 105. The solar panel 101 is installed at an angle according to its location, not only directly converting solar energy into DC power through the photovoltaic effect of semiconductor materials, but also acting as a sunshade to reduce heat radiation from the ground. The charge / discharge controller 105 manages the battery pack 103 to prevent overcharging or over-discharging. In this technical solution, the battery pack 103 uses either lithium-ion batteries or lithium iron phosphate batteries to balance capacity and cost.

[0039] Preferably, the power supply unit 100 further includes a wind turbine 107, which is electrically connected to the battery pack 103 via a charge / discharge controller 105. The wind turbine 107 is installed at a suitable height to utilize local wind energy.

[0040] It should be noted that the charge / discharge controller 105 is existing technology, and its specific structure will not be described in detail here.

[0041] Preferably, in this embodiment, the charge / discharge controller 105 is also electrically connected to the control unit 200, the compressor 350, and the multi-way valve 390. The charge / discharge controller 105 employs parallel MPPT (maximum power point tracking) technology to prioritize the scheduling of electrical energy, ensuring that the input renewable power is preferentially used to power the heat pump system 300, with the remaining energy used to charge the battery pack 103. When solar and wind power are insufficient, the battery pack 103 discharges to provide power to the heat pump system 300, ensuring continuous system operation.

[0042] Preferably, the control unit 200 is electrically connected to the charge / discharge controller 105 and can also monitor the voltage, current and local light intensity of the battery pack 103, thereby enabling communication management of the charge / discharge controller 105 and adjusting the power flow as needed.

[0043] Preferably, both the first exchange device 310 and the second exchange device 330 are composed of multiple metal tubes. These multiple metal tubes are arranged and welded together to form a passage. The arrangement type includes at least one of linear, annular, or planar configurations. The specific form of the first exchange device 310 and the second exchange device 330 is determined according to actual needs.

[0044] In one embodiment, the permafrost conservation experimental device provided by the present invention is deployed in a permafrost protection and restoration area or a scientific research experimental site.

[0045] Solar panels 101 are installed at an angle on the ground according to the maximum power point tracking principle to capture maximum solar energy; wind turbines 107 are installed at a suitable height to utilize local wind energy. The electrical energy generated by the solar panels 101 and wind turbines 107 is fed into a charge / discharge controller 105, which prioritizes the dispatch of electrical energy so that the input renewable power is used primarily to power the heat pump system 300, and the remaining energy is used to charge the battery pack 103.

[0046] When soil cooling is required in permafrost protection and restoration areas, assuming the current temperature detection unit 400 detects that the soil temperature exceeds a preset upper limit (e.g., 0℃ or higher), the system enters cooling mode. The control unit 200 commands the multi-way valve 390 to switch to cooling mode, connecting the first exchange unit 310 to the low-pressure side of the compression unit 350. The refrigerant acts as an evaporator in the first exchange unit 310, absorbing heat from the soil and evaporating. The evaporated low-pressure gas is drawn into the compression unit 350 and compressed into a high-temperature, high-pressure gas, which is then switched to the second exchange unit 330 via the multi-way valve 390. In the second exchange unit 330 (which acts as a condenser at this time), the refrigerant releases heat to the air and condenses into a liquid. After being throttled and depressurized by the expansion valve 370, the liquid refrigerant flows back to the first exchange unit 310 to continue absorbing heat, completing one cycle. During this process, heat is continuously extracted from the underground soil and released into the air, achieving the purpose of lowering the soil temperature. The control unit 200 can adjust the compressor frequency, expansion valve opening, etc., according to the real-time soil temperature and set value to avoid temperature overshoot or oscillation. The entire cooling process can continue to run until the soil temperature drops to within the target range.

[0047] When a warming test is required at a permafrost research and experimental site, if the soil temperature is below a preset lower limit, the system enters warming mode. Control unit 200 controls multi-way valve 390 to switch to warming mode, connecting the second exchange unit 330 to the low-pressure side of the compression unit 350. In this mode, the refrigerant first absorbs heat from the air and evaporates in the second exchange unit 330 (which acts as an evaporator). The low-pressure gaseous refrigerant is drawn into the compression unit 350 and compressed into a high-temperature, high-pressure gas, then introduced into the first exchange unit 310 (which acts as a condenser) through multi-way valve 390. In the first exchange unit 310, the high-temperature refrigerant releases heat to the surrounding soil and condenses. The condensed liquid refrigerant is then throttled by expansion valve 370 and returned to the second exchange unit 330 to continue absorbing heat. Through repeated cycles, heat from the surrounding air is carried into the underground soil by the refrigerant, and the soil temperature gradually increases. Control unit 200 can adjust the operating strategy according to the soil warming rate and target temperature to save energy and avoid overheating.

[0048] In this embodiment, the control unit 200 is equipped with a temperature hysteresis and safety mechanism: when the soil temperature approaches the set value, the control unit 200 can temporarily shut down the compressor 350 or switch to standby mode to prevent frequent switching; if the soil is too hot or too cold, the control unit 200 can automatically cut off the cooling cycle or issue an alarm. Simultaneously, the voltage and temperature of the battery pack 103 are also monitored to ensure safe charging and discharging and stable operation of the heat pump.

[0049] In another embodiment, the permafrost conservation experimental device provided by the present invention is deployed in a site where freeze-thaw alternation tests need to be conducted.

[0050] The heat pump system 300 is powered by solar panels 101 and wind turbine 107, which in turn power the charge / discharge controller 105 and battery pack 103. When the control unit 200 receives feedback from the temperature detection unit 400 that the target soil temperature is lower than the preset lower limit, it automatically switches to the heating mode: the second exchange device 330 acts as an evaporator to absorb heat from the air, and after being compressed by the compression device 350, the high-temperature and high-pressure refrigerant flows into the first exchange device 310 and condenses and releases heat there, thereby continuously transferring heat to the soil; the refrigerant, after being throttled and depressurized by the expansion valve 370, returns to the second exchange device 330 to absorb heat again. When the control unit 200 receives feedback from the temperature detection unit 400 that the target soil temperature exceeds the preset upper limit, it automatically switches to cooling mode: the first exchange device 310 acts as an evaporator, absorbing heat from the soil and causing the refrigerant to evaporate. After being compressed into a high-temperature, high-pressure gas by the compression device 350, it flows into the second exchange device 330, where it condenses and releases heat into the air. The condensed liquid refrigerant is then throttled and depressurized by the expansion valve 370 before re-entering the first exchange device 310 to continue absorbing heat. Through the repeated cycles of heating and cooling, the purpose of a controlled freeze-thaw alternation test on the soil is achieved.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An experimental device for permafrost conservation based on renewable energy and heat pumps, characterized in that, Includes a power supply unit, a control unit, a heat pump system, and a temperature detection unit; The power supply unit is electrically connected to the control unit and the heat pump system; The control unit is used to control the heat pump system and is electrically connected to the temperature detection unit; The heat pump system includes a first heat exchanger, a second heat exchanger, a compression unit, an expansion valve, and a multi-way valve. The first heat exchanger, the expansion valve, the second heat exchanger, the multi-way valve, and the compression unit are connected in sequence to form a passage. The first and second exchange devices are used to hold fluid refrigerant.

2. The experimental device for permafrost conservation based on renewable energy and heat pumps according to claim 1, characterized in that, The power supply unit includes a solar panel, a battery pack, and a charge / discharge controller. The solar panel is electrically connected to the battery pack through the charge / discharge controller.

3. The experimental device for permafrost conservation based on renewable energy and heat pumps according to claim 2, characterized in that, The power supply unit also includes a wind turbine, which is electrically connected to the battery pack via the charge / discharge controller.

4. An experimental device for permafrost conservation based on renewable energy and a heat pump according to claim 2 or 3, characterized in that, The control unit is electrically connected to the charge / discharge controller, and the control unit performs communication management of the charge / discharge controller.

5. The experimental device for permafrost conservation based on renewable energy and heat pumps according to claim 1, characterized in that, Both the first and second switching devices are composed of multiple metal tubes, which together form a passage.

6. The experimental device for permafrost conservation based on renewable energy and heat pumps according to claim 5, characterized in that, The first and second switching devices are laid out in at least one of the following patterns: linear, ring-shaped, or planar.

7. The experimental device for permafrost conservation based on renewable energy and heat pumps according to claim 1, characterized in that, The refrigerant is R600a or R717.

8. An experimental device for permafrost conservation based on renewable energy and a heat pump according to claim 2 or 3, characterized in that, The battery pack is a lithium-ion battery or a lithium iron phosphate battery.

9. An experimental device for permafrost conservation based on renewable energy and a heat pump according to claim 2 or 3, characterized in that, Both the multi-way valve and the compression device are electrically connected to the charge-discharge controller, which provides electrical energy to the multi-way valve and the compression device.

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