A composite thermosyphon for soil temperature regulation and its control method

Abstract

The present invention discloses a composite heat pipe for soil temperature regulation and its control method, which includes a solar photovoltaic device, a composite refrigeration device and a control module. The control module is respectively connected to the solar photovoltaic device and the composite refrigeration device. The solar photovoltaic device includes a solar photovoltaic panel, an electric energy controller, a storage battery, an inverter and an electric meter. The composite refrigeration device includes an air-cooled condenser, an electric valve, an electric expansion valve, a compressor, a self-standing three-way valve and a direct expansion evaporator. The control module includes a sensor and a controller. By sharing the condenser and the evaporator and ingeniously designing valves and refrigerant circulation pipelines, etc., the present invention can not only efficiently discharge the heat in the soil to low-temperature air, but also effectively discharge it to high-temperature air, realizing the economic efficiency of the device. The present invention can be widely applied in the field of temperature regulation devices.

Description

Technical Field

[0001] The present invention relates to the field of temperature control devices, and particularly to a composite heat pipe for soil temperature control and its control method. Background Art

[0002] In permafrost regions, thawing of permafrost in the warm season will cause adverse phenomena such as subgrade deformation, heaving and tilting, affecting the stability of high-speed railways, and even causing casualties in severe cases. Therefore, to ensure the stability and safety of subgrade engineering in permafrost regions, it is necessary to ensure the bearing capacity and thermal stability of permafrost, prevent the temperature of permafrost from rising, and avoid the thawing of the frozen soil layer.

[0003] To actively cool the subgrade and prevent the soil temperature in the permafrost region from rising, technologies such as block stone layers, ventilation pipes and heat pipes are currently mostly used. One section of the traditional heat pipe is buried in the soil, and the rest is exposed to the air. When the air temperature is significantly lower than the soil temperature, the liquid refrigerant in the soil section of the heat pipe is heated by the relatively warm soil, absorbs the heat of the soil and evaporates into a gas, rising to the air section; then, the gaseous refrigerant is condensed by the low-temperature air, releases the heat to the air and condenses into a liquid, and flows back to the soil section under the action of gravity. However, this type of technology is mainly applied under conditions where the atmospheric temperature is relatively low in the cold season, and resists the rise of soil temperature in the warm season through cold-season heat storage in the soil, and cannot achieve year-round cooling of the soil. Especially in the warm season with a high risk of permafrost degradation, the traditional heat pipe cannot operate and cannot specifically solve the problem of permafrost thawing in the warm season. Summary of the Invention

[0004] To solve the above technical problems, the object of the present invention is to provide a composite heat pipe for soil temperature control, which can use the heat siphon mode for refrigeration when the air temperature is relatively low in the cold season, and rely on the vapor compression mode for heat exchange in the warm season.

[0005] The first technical solution adopted by the present invention is: a composite heat pipe for soil temperature control, including a solar photovoltaic device, a composite refrigeration device and a control module. The control module is respectively connected to the solar photovoltaic device and the composite refrigeration device. The solar photovoltaic device includes a solar photovoltaic panel, a power controller, a storage battery, an inverter and an electric meter. The solar photovoltaic panel, the power controller, the inverter and the electric meter are connected in sequence. The power controller is also connected to the storage battery, and the power controller is connected to the control module. The composite refrigeration device includes an air-cooled condenser, a first switching module, a second switching module and a direct expansion evaporator. The air-cooled condenser and the direct expansion evaporator are respectively connected to the first switching module and the second switching module. The first switching module, the second switching module and the air-cooled condenser are respectively connected to the control module.

[0006] Further, the first switching module includes an electric valve and an electronic expansion valve. The electric valve and the electronic expansion valve are respectively connected to the air-cooled condenser, the direct expansion evaporator, and the control module.

[0007] Further, the second switching module includes a compressor and a self-operated three-way valve. The compressor and the self-operated three-way valve are respectively connected to the air-cooled condenser, the direct expansion evaporator, and the control module.

[0008] Further, the control module includes a temperature sensor and a controller. The temperature sensor is connected to the controller, and the controller is respectively connected to the electric valve, the electronic expansion valve, the compressor, the self-operated three-way valve, the air-cooled condenser, and the electric energy controller.

[0009] The second technical solution adopted by the present invention is: a control method for a composite heat pipe for soil temperature regulation, including the following steps:

[0010] Obtain ambient air temperature information, soil temperature information, and solar photovoltaic panel power generation information;

[0011] Switch the working mode of the composite heat pipe according to the ambient air temperature information, soil temperature information, solar photovoltaic panel power generation information, and preset rules.

[0012] Further, the step of switching the working mode of the composite heat pipe according to the ambient air temperature information, soil temperature information, solar radiation intensity information, and preset rules specifically includes:

[0013] When it is determined that the soil temperature is lower than the preset temperature and the power generation of the solar photovoltaic panel is greater than the first preset power generation, the composite refrigeration equipment does not operate, and the working mode of the composite heat pipe is switched to the solar power storage mode;

[0014] When it is determined that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, and the power generation of the solar photovoltaic panel is greater than the first preset power generation, the working mode of the composite heat pipe is switched to the solar power supply and thermosiphon mode;

[0015] When it is determined that the ambient air temperature is higher than the soil temperature, the soil temperature is higher than the preset temperature, and the power generation of the solar photovoltaic panel is greater than the second preset power generation, the working mode of the composite heat pipe is switched to the solar power supply and vapor compression mode;

[0016] When it is determined that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is less than the first preset power generation, and the power generation of the battery is higher than the first preset power generation, the working mode of the composite heat pipe is switched to the battery power supply and thermosiphon mode;

[0017] When it is determined that the ambient air temperature is higher than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is less than the second preset power generation, and the power generation of the storage battery is higher than the second preset power generation, switch the working mode of the composite heat pipe to the power supply of the storage battery and the vapor compression mode;

[0018] When it is determined that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is greater than the first preset power generation, the power generation of the storage battery is less than the first preset power generation, and the combined power generation of solar energy and the storage battery is greater than the first preset power generation, switch the working mode of the composite heat pipe to the combined power supply of solar energy and the storage battery and the heat siphon mode;

[0019] When it is determined that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is greater than the second preset power generation, the power generation of the storage battery is less than the second preset power generation, and the combined power generation of solar energy and the storage battery is greater than the second preset power generation, switch the working mode of the composite heat pipe to the combined power supply of solar energy and the storage battery and the vapor compression mode;

[0020] Otherwise, the composite heat pipe does not operate.

[0021] Furthermore, the working modes of the composite heat pipe specifically include:

[0022] Solar energy storage mode, in which the composite refrigeration device in this mode does not operate, and the storage battery receives the power generated by the solar photovoltaic panel;

[0023] Solar energy power supply and heat siphon mode, in which this mode is powered by the solar photovoltaic panel, the compressor and the electric expansion valve are closed, only the fan of the air-cooled condenser consumes power, the liquid refrigerant absorbs heat from the soil in the direct expansion evaporator and evaporates into a gaseous refrigerant, the gaseous refrigerant passes through the electric valve and enters the air-cooled condenser on the ground surface, the gaseous refrigerant in the condenser is condensed into a liquid refrigerant by the ambient low-temperature air, releases heat, and flows into the direct expansion evaporator through the self-acting three-way valve to complete the heat siphon mode cycle. If there is surplus power, it can enter the storage battery for storage;

[0024] Solar energy power supply and vapor compression mode, in which this mode is powered by the solar photovoltaic panel, the compressor operates, the self-acting three-way valve opens the compressor loop, the electric expansion valve opens, and the electric valve closes. The low-temperature and low-pressure liquid refrigerant absorbs heat from the soil in the direct expansion evaporator and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor to be compressed into a high-temperature and high-pressure gas, then enters the air-cooled condenser to be cooled to a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve to expand into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator to complete the vapor compression mode cycle. If there is surplus power, it can enter the storage battery for storage;

[0025] Battery-powered and thermosiphon mode, in which the system is powered by a battery, the compressor and the electric expansion valve are closed, only the fan of the air-cooled condenser consumes power. The refrigerant in the direct expansion evaporator absorbs heat from the soil and evaporates into gaseous refrigerant. The gaseous refrigerant passes through the electric valve and enters the air-cooled condenser on the ground surface. The gaseous refrigerant in the condenser is condensed into liquid refrigerant by the low-temperature ambient air, releases heat, and flows into the direct expansion evaporator through the self-operated three-way valve to complete the thermosiphon mode cycle;

[0026] Battery-powered and vapor compression mode, in which the system is powered by a battery, the compressor operates, the self-operated three-way valve opens the compressor loop, the electric expansion valve opens, and the electric valve closes. The low-temperature and low-pressure liquid refrigerant in the direct expansion evaporator absorbs heat from the soil and becomes low-temperature and low-pressure gaseous refrigerant, enters the compressor and is compressed into high-temperature and high-pressure gas, then enters the air-cooled condenser to be cooled to high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve to expand into low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator to complete the vapor compression mode cycle;

[0027] Solar energy combined with battery-powered and thermosiphon mode, in which the system is powered by solar photovoltaic panels and a battery together, the compressor and the electric expansion valve are closed, only the fan of the air-cooled condenser consumes power. The liquid refrigerant in the composite refrigeration device absorbs heat from the soil in the direct expansion evaporator and evaporates into gaseous refrigerant. The gaseous refrigerant passes through the electric valve and enters the air-cooled condenser on the ground surface. The gaseous refrigerant in the condenser is condensed into liquid refrigerant by the low-temperature ambient air, releases heat, and flows into the direct expansion evaporator through the self-operated three-way valve to complete the thermosiphon mode cycle;

[0028] Solar energy combined with battery-powered and vapor compression mode, in which the system is powered by solar photovoltaic panels and a battery together, the compressor operates, the self-operated three-way valve opens the compressor loop, the electric expansion valve opens, and the electric valve closes. The low-temperature and low-pressure liquid refrigerant in the composite refrigeration device absorbs heat from the soil in the direct expansion evaporator and becomes low-temperature and low-pressure gaseous refrigerant, enters the compressor and is compressed into high-temperature and high-pressure gas, then enters the air-cooled condenser to be cooled to high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve to expand into low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator to complete the vapor compression mode cycle.

[0029] The beneficial effects of the method of the present invention are as follows: Compared with traditional heat pipes, the function of vapor compression is added. It can rely on the thermosiphon mode for refrigeration when the air temperature is relatively low in the cold season, and rely on the vapor compression mode for heat exchange in the warm season. It can not only efficiently discharge the heat in the soil to the low-temperature air, but also effectively discharge it to the high-temperature air. In addition, the composite heat pipe is not a simple superposition of two systems of thermosiphon technology and vapor compression technology, but realizes the economic efficiency of the device by sharing the condenser and evaporator, and ingeniously designing valves and refrigerant circulation pipelines, etc. Description of the Drawings

[0030] Figure 1 is a diagram of a composite heat pipe device for soil temperature regulation according to the present invention;

[0031] Figure 2 is a schematic diagram of the operating mode switching of a composite heat pipe for soil temperature regulation according to the present invention;

[0032] Figure 3 is a partial circuit diagram of the controller in a specific embodiment of the present invention;

[0033] Reference numerals: 1, solar photovoltaic panel; 2, power controller; 3, battery; 4, inverter; 5, electric meter; 6, air-cooled condenser; 7, electric valve; 8, electric expansion valve; 9, compressor; 10, self-standing three-way valve; 11, direct expansion evaporator; 12, controller; 13, temperature sensor. Detailed Embodiments

[0034] The following further describes the present invention in detail with reference to the drawings and specific embodiments. For the step numbers in the following embodiments, they are only set for the convenience of elaboration and explanation, and no limitation is imposed on the order between steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0035] As Figure 1 shown, the present invention provides a composite heat pipe for soil temperature regulation, including a solar photovoltaic device, a composite refrigeration device and a control module. The control module is respectively connected to the solar photovoltaic device and the composite refrigeration device. The solar photovoltaic device includes a solar photovoltaic panel 1, a power controller 2, a battery 3, an inverter 4 and an electric meter 5. The solar photovoltaic panel 1, the power controller 2, the inverter 4 and the electric meter 5 are connected in sequence. The power controller 2 is also connected to the battery 3. The power controller 2 is connected to the control module. The composite refrigeration device includes an air-cooled condenser 6, a first switching module, a second switching module and a direct expansion evaporator 11. The air-cooled condenser 6 and the direct expansion evaporator 11 are respectively connected to the first switching module and the second switching module. The first switching module, the second switching module and the air-cooled condenser are respectively connected to the control module.

[0036] Specifically, under the radiation of the sun, the solar photovoltaic panel 1 can generate electricity, and the generated electric energy is supplied to the composite refrigeration device through the electric energy controller 2. If there is still surplus electric energy, it will be stored in the storage battery 3 through the adjustment of the electric energy controller 2. The storage battery 3 plays the role of storing electric energy and balancing the load. During the process of supplying electric energy to the composite refrigeration device, an inverter 4 is needed to convert the direct current generated by the solar photovoltaic panel 1 into alternating current for supply to drive the compressor 9 and the condenser fan of the refrigeration module. The electricity meter 5 is used for the measurement of electric energy.

[0037] Further as a preferred embodiment, the first switching module includes an electric valve 7 and an electronic expansion valve 8. The electric valve 7 and the electronic expansion valve 8 are respectively connected to the air-cooled condenser 6, the electric valve 7 and the electronic expansion valve 8 are respectively connected to the direct expansion evaporator 11, and the electric valve 7 and the electronic expansion valve 8 are respectively connected to the control module.

[0038] Further as a preferred embodiment, the second switching module includes a compressor 9 and a self-operated three-way valve 10. The compressor 9 and the self-operated three-way valve 10 are respectively connected to the air-cooled condenser 6, the compressor 9 and the self-operated three-way valve 10 are respectively connected to the direct expansion evaporator 11, and the compressor 9 and the self-operated three-way valve 10 are respectively connected to the control module.

[0039] Further as a preferred embodiment, the control module includes a temperature sensor 13 and a controller 12. The temperature sensor 13 is connected to the controller 12. The controller 12 is respectively connected to the electric valve 7, the electronic expansion valve 8, the compressor 9, the self-operated three-way valve 10, the air-cooled condenser 6 and the electric energy controller 2. The temperature sensor 13 includes a first temperature sensor and a second temperature sensor. The first temperature sensor is used to detect the ambient air temperature, and the second temperature sensor is used to detect the soil temperature.

[0040] Specifically, when the ambient air temperature in the frozen soil area is significantly lower than the surface soil temperature, the compressor 9 of the composite refrigeration device does not operate. The self-operated three-way valve 10 automatically connects the outlet of the air-cooled condenser 6 and the inlet pipeline of the direct expansion evaporator 11. The electric expansion valve 8 is closed, and the electric valve 7 is opened, and the device operates in the thermosyphon mode. In this mode, only the fan of the condenser 6 in the composite refrigeration device operates, and the power consumption is less. The air-cooled condenser 6 and the direct expansion evaporator 11 form a separated thermosyphon tube, and under the drive of the natural temperature difference between the air and the soil, the heat in the soil is discharged into the air. At this time, the liquid refrigerant in the composite refrigeration device absorbs the heat in the soil in the direct expansion evaporator 11 and evaporates into a gaseous refrigerant. The gaseous refrigerant passes through the electric valve 7 and enters the air-cooled condenser 6 on the ground surface. The gaseous refrigerant in the condenser 6 is condensed into a liquid refrigerant by the ambient low-temperature air, releases heat, and flows into the direct expansion evaporator 11 through the self-operated three-way valve 10 to complete the thermosyphon mode cycle.

[0041] When the ambient air temperature in the frozen soil area is higher than or only slightly lower than the surface soil temperature, the compressor 9 of the composite refrigeration device operates. The self-operated three-way valve 10 opens the compressor loop. The electric expansion valve 8 is opened, and the electric valve 7 is closed, and the device operates in the compression refrigeration mode. In this mode, the composite refrigeration device can generate a large amount of refrigeration capacity and a low evaporation temperature under the drive of the electric energy of the compressor 9 to quickly cool the soil. At this time, the low-temperature and low-pressure liquid refrigerant in the composite refrigeration device absorbs the heat in the soil in the direct expansion evaporator 11 and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor 9 and is compressed into a high-temperature and high-pressure gas, then enters the air-cooled condenser 6 to be cooled into a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve 8 and expands into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator 11 to complete the vapor compression mode cycle.

[0042] The working principle of this composite heat pipe is as follows: The composite heat pipe for regulating soil temperature uses solar energy as the driving energy source to efficiently discharge the heat in the soil in the permafrost area into the air at different temperatures. The solar photovoltaic module can convert solar energy into electrical energy, and through the regulation of the electrical energy controller and the storage battery, the power consumption under different operating conditions can be balanced. The composite refrigeration device can operate in the thermosiphon mode and the vapor compression mode. In the thermosiphon mode, only the fan of the air-cooled condenser in the composite refrigeration device operates, and the compressor is turned off. With only a small amount of electrical energy, efficient regulation of soil temperature can be achieved. In the vapor compression mode, both the compressor and the fan of the composite refrigeration device operate, which can increase the refrigeration capacity and lower the refrigeration temperature, realizing large-capacity regulation of soil temperature. The composite heat pipe for regulating soil temperature can operate in different modes according to conditions such as solar radiation intensity, air temperature, and user requirements. It can switch between multiple modes by starting and stopping the compressor and opening and closing the valves, including: solar power storage mode, solar power supply and thermosiphon mode, solar power supply and vapor compression mode, battery power supply and thermosiphon mode, battery power supply and vapor compression mode, solar combined with battery power supply and thermosiphon mode, solar combined with battery power supply and vapor compression mode.

[0043] The described composite heat pipe for soil temperature regulation can achieve the following several independent operating modes, such as Figure 2 shown as:

[0044] 1. Solar power storage mode: When the solar radiation is strong, the solar photovoltaic panel 1 generates more electricity. If the soil temperature in the permafrost area is low at this time and refrigeration is not required, the refrigeration device may not operate, and the electricity generated by the solar energy is directly stored in the storage battery 3.

[0045] 2. Solar power supply and thermosiphon mode: When the ambient air temperature is significantly lower than the soil temperature and the soil needs refrigeration, the refrigeration device operates in the thermosiphon mode. At this time, if the solar radiation is strong and the generated electricity can meet the requirements of this mode, the composite heat pipe operates in the solar power supply and thermosiphon mode. The compressor 9 and the electric expansion valve 8 in this mode are closed, and only the fan of the air-cooled condenser 6 consumes electricity. The liquid refrigerant in the composite refrigeration device absorbs the heat in the soil in the direct expansion evaporator 11 and evaporates into a gaseous refrigerant. The gaseous refrigerant passes through the electric valve 7 and enters the air-cooled condenser 6 on the ground surface. The gaseous refrigerant in the condenser is condensed into a liquid refrigerant by the low-temperature ambient air, releases heat, and flows into the direct expansion evaporator 11 through the self-acting three-way valve 10 to complete the thermosiphon mode cycle. If there is surplus electricity, it can enter the storage battery for power storage.

[0046] 3 Solar power supply and vapor compression mode: When the ambient air temperature is higher than the soil temperature and the soil needs cooling, the refrigeration device operates in the vapor compression mode. At this time, if the solar radiation is strong and the generated electricity can meet the demand of this mode, the composite heat pipe operates in the solar power supply and vapor compression mode. In this mode, the compressor 9 operates, the self-operated three-way valve 10 opens the compression loop, the electric expansion valve 8 opens, and the electric valve 7 closes. The low-temperature and low-pressure liquid refrigerant in the composite refrigeration device absorbs the heat in the soil in the direct expansion evaporator 11 and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor 9 and is compressed into a high-temperature and high-pressure gaseous refrigerant, then enters the air-cooled condenser 6 and is cooled to a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve 8 and expands into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator 11 to complete the vapor compression mode cycle. If there is surplus electricity, it can be stored in the battery.

[0047] 4 Battery power supply and thermosiphon mode: When the ambient air temperature is significantly lower than the soil temperature and the soil needs cooling, the refrigeration device operates in the thermosiphon mode. At this time, if the solar radiation intensity is almost zero and normal power generation is impossible, and the battery 3 has stored electricity that can meet the demand of this mode, the composite heat pipe operates in the battery power supply and thermosiphon mode. In this mode, the compressor 9 and the electric expansion valve 8 are closed, and only the fan of the air-cooled condenser 6 consumes electricity. The liquid refrigerant in the composite refrigeration device absorbs the heat in the soil in the direct expansion evaporator 11, evaporates into a gaseous refrigerant, the gaseous refrigerant passes through the electric valve 7, enters the air-cooled condenser 6 on the ground surface, the gaseous refrigerant in the condenser 6 is condensed into a liquid refrigerant by the ambient low-temperature air, releases heat, and flows into the direct expansion evaporator 11 through the self-operated three-way valve 10 to complete the thermosiphon mode cycle.

[0048] 5 Battery power supply and vapor compression mode: When the ambient air temperature is higher than the soil temperature and the soil needs cooling, the refrigeration device operates in the vapor compression mode. At this time, if the solar radiation intensity is almost zero and normal power generation is impossible, and the battery has stored electricity that can meet the demand of this mode, the composite heat pipe operates in the battery power supply and vapor compression mode. In this mode, the compressor 9 operates, the self-operated three-way valve 10 opens the compressor loop, the electric expansion valve 8 opens, and the electric valve 7 closes. The low-temperature and low-pressure liquid refrigerant in the composite refrigeration device absorbs the heat in the soil in the direct expansion evaporator 11 and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor 9 and is compressed into a high-temperature and high-pressure gaseous refrigerant, then enters the air-cooled condenser 6 and is cooled to a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve 8 and expands into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator 11 to complete the vapor compression mode cycle.

[0049] 6 Solar combined battery power supply and thermosiphon mode: When the ambient air temperature is significantly lower than the soil temperature and the soil needs to be cooled, the refrigeration device operates in the thermosiphon mode. At this time, if the solar radiation intensity is not high and the generated electricity cannot fully meet the operation of the thermosiphon mode, and there is stored electricity in the battery 3, the battery 3 can supply power together with the solar photovoltaic panel 1, then the composite heat pipe operates in the solar combined battery power supply and thermosiphon mode. In this mode, the compressor 9 and the electric expansion valve 8 are closed, and only the fan of the air-cooled condenser 6 consumes electricity. The liquid refrigerant in the composite refrigeration device absorbs heat from the soil in the direct expansion evaporator 11 and evaporates into a gaseous refrigerant. The gaseous refrigerant passes through the electric valve 7 and enters the air-cooled condenser 6 on the ground surface. The gaseous refrigerant in the condenser 6 is condensed into a liquid refrigerant by the low-temperature ambient air, releases heat, and flows into the direct expansion evaporator 11 through the self-acting three-way valve 10 to complete the thermosiphon mode cycle.

[0050] 7 Solar combined battery power supply and vapor compression mode: When the ambient air temperature is higher than the soil temperature and the soil needs to be cooled, the refrigeration device operates in the vapor compression mode. If the solar radiation intensity is not high and the generated electricity cannot fully meet the operation of the vapor compression mode, and there is stored electricity in the battery 3, the battery 3 can supply power together with the solar photovoltaic panel 1, then the composite heat pipe operates in the solar combined battery power supply and vapor compression mode. In this mode, the compressor 9 operates, the self-acting three-way valve 10 opens the compressor loop, the electric expansion valve 8 opens, and the electric valve 7 closes. The low-temperature and low-pressure liquid refrigerant in the composite refrigeration device absorbs heat from the soil in the direct expansion evaporator 11 and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor 9 and is compressed into a high-temperature and high-pressure gas, then enters the air-cooled condenser 6 to be cooled to a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve 8 and expands into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator 11 to complete the vapor compression mode cycle.

[0051] To achieve the switching of the above 7 operating modes, it can be realized by a voltage comparator and logic gates. Specifically, refer to Figure 3, the output value of the second temperature sensor is less than the first reference voltage, and the second comparator U2 outputs a low level; the power generation of the inverter is greater than the second reference voltage, and the voltage comparator U3 outputs a high level, and the solar energy storage mode is operated. The output value of the first temperature sensor is less than the output value of the second temperature sensor, and the first comparator U1 outputs a low level; the output value of the second temperature sensor is greater than the first reference voltage, and the second comparator U2 outputs a high level; the power generation of the inverter is greater than the second reference voltage, and the third comparator U3 outputs a high level, and the solar power supply and thermosiphon mode is operated. The output value of the first temperature sensor is greater than the output value of the second temperature sensor, and the first comparator U1 outputs a high level; the output value of the second temperature sensor is greater than the first reference voltage, and the second comparator U2 outputs a high level; the power generation of the inverter is greater than the third reference voltage, and the fourth comparator U4 outputs a high level, and the solar power supply and vapor compression mode is operated. The output value of the first temperature sensor is less than the output value of the second temperature sensor, and the first comparator U1 outputs a low level; the output value of the second temperature sensor is greater than the first reference voltage, and the second comparator U2 outputs a high level; the power generation of the inverter is less than the second reference voltage, and the third comparator U3 outputs a low level; the power supply of the battery is higher than the second reference voltage, and the fifth comparator U5 outputs a high level, and the battery power supply and thermosiphon mode is operated. The output value of the first temperature sensor is greater than the output value of the second temperature sensor, and the first comparator U1 outputs a high level; the output value of the second temperature sensor is greater than the first reference voltage, and the second comparator U2 outputs a high level; the power generation of the inverter is less than the third reference voltage, and the fourth comparator U4 outputs a low level; the power supply of the battery is higher than the third reference voltage, and the sixth comparator U6 outputs a high level, and the battery power supply and vapor compression mode is operated. The output value of the first temperature sensor is less than the output value of the second temperature sensor, and the first comparator U1 outputs a low level; the output value of the second temperature sensor is greater than the first reference voltage, and the second comparator U2 outputs a high level; the power generation of the inverter is less than the second reference voltage, and the third comparator U3 outputs a low level; the power supply of the battery is lower than the second reference voltage, and the fifth comparator U5 outputs a low level; the combined power generation of the inverter and the battery is greater than the second reference voltage, and the seventh comparator U7 outputs a high level, then the solar energy combined with battery power supply and thermosiphon mode is operated. The output value of the first temperature sensor is greater than the output value of the second temperature sensor, and the first comparator U1 outputs a high level; the output value of the second temperature sensor is greater than the first reference voltage, and the second comparator U2 outputs a high level; the power generation of the inverter is less than the third reference voltage, and the fourth comparator U4 outputs a low level; the power supply of the battery is lower than the third reference voltage, and the sixth comparator U6 outputs a low level; the combined power generation of the inverter and the battery is greater than the third reference voltage, and the eighth comparator U8 outputs a high level, then the solar energy combined with battery power supply and vapor compression mode is operated.

[0052] The above is a specific description of the preferred embodiment of the present invention. However, the present invention is not limited to the described embodiment. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A composite heat pipe for soil temperature regulation, characterized in that, It includes a solar photovoltaic device, a composite refrigeration device and a control module. The control module is respectively connected to the solar photovoltaic device and the composite refrigeration device. The solar photovoltaic device includes a solar photovoltaic panel, a power controller, a storage battery, an inverter and an ammeter. The solar photovoltaic panel, the power controller, the inverter and the ammeter are connected in sequence. The power controller is also connected to the storage battery. The power controller is connected to the control module. The composite refrigeration device includes an air-cooled condenser, a first switching module, a second switching module and a direct expansion evaporator. The air-cooled condenser and the direct expansion evaporator are respectively connected to the first switching module and the second switching module. The first switching module, the second switching module and the air-cooled condenser are respectively connected to the control module; The control method of the composite heat pipe is as follows: Obtain ambient air temperature information, soil temperature information and solar photovoltaic panel power generation information; Switch the working mode of the composite heat pipe according to the ambient air temperature information, soil temperature information, solar photovoltaic panel power generation information and preset rules; The step of switching the working mode of the composite heat pipe according to the ambient air temperature information, soil temperature information, solar radiation intensity information and preset rules specifically includes: When it is judged that the soil temperature is lower than the preset temperature and the power generation of the solar photovoltaic panel is greater than the first preset power generation, and the composite refrigeration equipment does not operate, switch the working mode of the composite heat pipe to the solar power storage mode; When it is judged that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, and the power generation of the solar photovoltaic panel is greater than the first preset power generation, switch the working mode of the composite heat pipe to the solar power supply and thermosyphon mode; When it is judged that the ambient air temperature is higher than the soil temperature, the soil temperature is higher than the preset temperature, and the power generation of the solar photovoltaic panel is greater than the second preset power generation, switch the working mode of the composite heat pipe to the solar power supply and vapor compression mode; When it is judged that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is less than the first preset power generation, and the power generation of the storage battery is higher than the first preset power generation, switch the working mode of the composite heat pipe to the storage battery power supply and thermosyphon mode; When it is judged that the ambient air temperature is higher than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is less than the second preset power generation, and the power generation of the storage battery is higher than the second preset power generation, switch the working mode of the composite heat pipe to the storage battery power supply and vapor compression mode; When it is judged that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is less than the first preset power generation, the power generation of the storage battery is less than the first preset power generation, and the combined power generation of the solar energy and the storage battery is greater than the first preset power generation, switch the working mode of the composite heat pipe to the combined power supply of solar power generation and storage battery and thermosyphon mode; When it is determined that the ambient air temperature is lower than the soil temperature, the soil temperature is higher than the preset temperature, the power generation of the solar photovoltaic panel is greater than the second preset power generation, the power generation of the battery is less than the second preset power generation, and the combined power generation of solar energy and the battery is greater than the second preset power generation, switch the working mode of the composite heat pipe to solar energy combined with battery power supply and vapor compression mode; Otherwise, the composite heat pipe does not operate; The working modes of the composite heat pipe specifically include: Solar energy storage mode, in which the composite refrigeration device in this mode does not operate, and the battery receives the power generated by the solar photovoltaic panel; Solar energy power supply and thermosiphon mode, in this mode, it is powered by the solar photovoltaic panel, the compressor and the electric expansion valve are closed, only the fan of the air-cooled condenser consumes power, the liquid refrigerant absorbs heat from the soil in the direct expansion evaporator and evaporates into a gaseous refrigerant, the gaseous refrigerant passes through the electric valve and enters the air-cooled condenser on the ground surface, the gaseous refrigerant in the condenser is condensed into a liquid refrigerant by the ambient low-temperature air, releases heat, and flows into the direct expansion evaporator through the self-acting three-way valve to complete the thermosiphon mode cycle. If there is surplus power, it can enter the battery for storage; Solar energy power supply and vapor compression mode, in this mode, it is powered by the solar photovoltaic panel, the compressor operates, the self-acting three-way valve opens the compressor loop, the electric expansion valve opens, and the electric valve closes. The low-temperature and low-pressure liquid refrigerant absorbs heat from the soil in the direct expansion evaporator and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor and is compressed into a high-temperature and high-pressure gas, then enters the air-cooled condenser to be cooled to a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve and expands into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator to complete the vapor compression mode cycle. If there is surplus power, it can enter the battery for storage; Battery power supply and thermosiphon mode, in this mode, it is powered by the battery, the compressor and the electric expansion valve are closed, only the fan of the air-cooled condenser consumes power, the liquid refrigerant absorbs heat from the soil in the direct expansion evaporator and evaporates into a gaseous refrigerant, the gaseous refrigerant passes through the electric valve and enters the air-cooled condenser on the ground surface, the gaseous refrigerant in the condenser is condensed into a liquid refrigerant by the ambient low-temperature air, releases heat, and flows into the direct expansion evaporator through the self-acting three-way valve to complete the thermosiphon mode cycle; Battery power supply and vapor compression mode, in this mode, it is powered by the battery, the compressor operates, the self-acting three-way valve opens the compressor loop, the electric expansion valve opens, and the electric valve closes. The low-temperature and low-pressure liquid refrigerant absorbs heat from the soil in the direct expansion evaporator and becomes a low-temperature and low-pressure gaseous refrigerant, enters the compressor and is compressed into a high-temperature and high-pressure gas, then enters the air-cooled condenser to be cooled to a high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve and expands into a low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator to complete the vapor compression mode cycle; Solar combined with battery power supply and thermosiphon mode. In this mode, the solar photovoltaic panel and the battery supply power together. The compressor and the electric expansion valve are closed, and only the fan of the air-cooled condenser consumes power. The liquid refrigerant in the composite refrigeration device absorbs heat from the soil in the direct expansion evaporator and evaporates into gaseous refrigerant. The gaseous refrigerant passes through the electric valve and enters the air-cooled condenser on the ground surface. The gaseous refrigerant in the condenser is condensed into liquid refrigerant by the low-temperature ambient air, releases heat, and flows into the direct expansion evaporator through the self-acting three-way valve to complete the thermosiphon mode cycle; Solar combined with battery power supply and vapor compression mode. In this mode, the solar photovoltaic panel and the battery supply power together. The compressor operates, the self-acting three-way valve opens the compressor loop, the electric expansion valve opens, and the electric valve closes. The low-temperature and low-pressure liquid refrigerant in the composite refrigeration device absorbs heat from the soil in the direct expansion evaporator and becomes low-temperature and low-pressure gaseous refrigerant, enters the compressor and is compressed into high-temperature and high-pressure gas, then enters the air-cooled condenser to be cooled to high-temperature and high-pressure liquid, releases heat to the surrounding high-temperature air, then enters the electronic expansion valve to expand into low-temperature and low-pressure liquid refrigerant, and then enters the direct expansion evaporator to complete the vapor compression mode cycle; Among them, the thermosiphon mode and the vapor compression mode share the condenser and the evaporator; The first switching module includes an electric valve and an electric expansion valve. The electric valve and the electric expansion valve are respectively connected to the air-cooled condenser, the electric valve and the electric expansion valve are respectively connected to the direct expansion evaporator, and the electric valve and the electric expansion valve are respectively connected to the control module; The second switching module includes a compressor and a self-acting three-way valve. The compressor and the self-acting three-way valve are respectively connected to the air-cooled condenser, the compressor and the self-acting three-way valve are respectively connected to the direct expansion evaporator, and the compressor and the self-acting three-way valve are respectively connected to the control module; The control module includes a temperature sensor and a controller. The temperature sensor is connected to the controller, and the controller is respectively connected to the electric valve, the electric expansion valve, the compressor, the self-acting three-way valve, the air-cooled condenser and the power controller.

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