Off-grid direct current refrigeration device for protecting permafrost
By using photovoltaic and wind power to drive a DC brushless electric compressor, the permafrost can be cooled directly, solving the problems of high starting current and high energy consumption, and achieving stability and economic improvement in permafrost protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHIJIAZHUANG TIEDAO UNIV
- Filing Date
- 2025-09-05
- Publication Date
- 2026-07-24
AI Technical Summary
Existing permafrost protection technologies have problems such as large starting current surges and high energy consumption when applied to the Qinghai-Tibet Plateau, especially in the absence of power grid supply. This leads to increased equipment costs and limits the large-scale application of artificial refrigeration technology for permafrost.
The system uses photovoltaic power generation equipment and wind turbines to generate electricity, stores the electrical energy in batteries, and drives a DC compressor. This eliminates the inverter stage and directly drives a DC brushless electric compressor. Combined with a cooling unit, it refrigerates permafrost, achieving efficient utilization of DC power.
It reduces current surges, lowers energy consumption, improves the operational stability and economy of refrigeration equipment, adapts to the harsh environment of the Qinghai-Tibet Plateau, and reduces equipment investment and operating costs.
Smart Images
Figure CN224551822U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of permafrost protection engineering technology, and specifically relates to an off-grid DC refrigeration device for protecting permafrost. Background Technology
[0002] The main challenge facing long-distance linear engineering projects such as transportation, power, and oil pipelines on the Qinghai-Tibet Plateau in my country is the thermal stability of permafrost foundations. This is because, under global warming conditions, permafrost on the Qinghai-Tibet Plateau generally exhibits a trend of warming and degradation. As temperatures rise, the ground thaws and settles, leading to deformation and damage to the superstructure. Roadbeds, bridge abutments, pile foundations, and power tower foundations, among other structures, suffer from settlement, cracking, and tilting due to the thaw deformation of permafrost foundations. Therefore, protecting permafrost is crucial for improving the construction and operation and maintenance of various infrastructure projects on the plateau.
[0003] Conventional permafrost protection primarily employs passive insulation measures such as sunshades and insulation layers, and active cooling measures such as heat pipes, boulders-cooled structures, and ventilation ducts. These measures do not require external energy consumption, relying on reducing heat from the climate environment during warm seasons and increasing cold from the climate environment during cold seasons. Therefore, the effectiveness of permafrost protection is limited by climatic conditions, making it difficult to actively control the cooling capacity and temperature drop, and sometimes failing to meet the foundation deformation control requirements of railway speed increases and highway operation. To address this, the industry has begun to introduce artificial refrigeration technology to force-cool permafrost. For example, application number CN201711190185.7 discloses a compression refrigeration device driven by AC power. This technology has been applied to the Qinghai-Tibet Railway, Qinghai-Tibet Highway, and Qinghai S224, among other lines. While it significantly improves the real-time performance and efficiency of permafrost protection, it also has two shortcomings: First, the large deviation between the actual operating environment and the rated operating conditions leads to unstable operation. Second, the large current surge during startup of the AC electric compressor inside the device, approximately 3-5 times the normal operating current, coupled with high energy consumption during normal operation, results in high power supply capacity requirements and excessively high power supply costs.
[0004] To address the first issue mentioned above, application number CN202510074208.6 discloses a weather-resistant refrigeration system for the Qinghai-Tibet Plateau, which uses specially designed high-altitude environmental performance enhancement components to adapt the refrigeration device to the drastically fluctuating climate of the plateau. However, it does not solve the second problem mentioned earlier, namely, the large starting current surge and high operating energy consumption of the device. Especially in areas along transportation routes and oil pipelines where there is no grid power supply, and where off-grid photovoltaic and wind power modules are required, it is necessary to increase the design capacity of energy storage and inverter devices, leading to a sharp increase in cost and limiting the large-scale application of artificial refrigeration technology in permafrost. Therefore, while improving the operational stability of refrigeration systems in high-altitude environments, it is urgent to improve equipment start-up performance and reduce energy consumption. Utility Model Content
[0005] To address the above problems, this utility model provides an off-grid DC refrigeration device for protecting permafrost.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: An off-grid DC refrigeration device for protecting permafrost includes an off-grid power supply unit, a refrigeration unit, and a cooling transmission unit placed within the permafrost. The off-grid power supply unit includes a photovoltaic power generation device, a wind turbine generator, a battery, a charge / discharge controller, and a frequency converter. The photovoltaic power generation device and the wind turbine generator are electrically connected to the battery. The battery is electrically connected to the DC compressor of the refrigeration unit, and the refrigeration unit is connected to the cooling transmission unit, which is used to refrigerate the permafrost.
[0007] Furthermore, the photovoltaic power generation equipment and the wind turbine are connected in parallel to the input electrode of the charge-discharge controller, the energy storage electrode of the charge-discharge controller is connected to the battery, the output electrode of the charge-discharge controller is connected to the input of the frequency converter, and the output of the frequency converter is connected to the DC compressor of the refrigeration unit.
[0008] Furthermore, the photovoltaic power generation equipment and wind turbine are mounted on a column, with the wind turbine mounted at the top of the column and the photovoltaic modules of the photovoltaic power generation equipment mounted in the upper middle part of the column.
[0009] Furthermore, the refrigeration unit includes a DC compressor, a condenser, a liquid receiver dryer, a throttle valve, and an evaporator. The DC compressor, condenser, liquid receiver dryer, throttle valve, evaporator, and DC compressor are sequentially connected through a medium pipeline to form a closed loop, which is filled with refrigerant. The DC compressor, condenser, liquid receiver dryer, and throttle valve are located inside a cabinet, and the evaporator is located inside a cooling unit.
[0010] Furthermore, the DC compressor is a DC brushless electric compressor with a rated power supply of 24V.
[0011] Furthermore, the cooling unit includes a buried casing and mortar backfill material. The evaporator is installed inside the buried casing and is divided into a straight section and a spiral section, both of which are installed inside the buried casing. The mortar backfill material fills the space between the buried casing and the permafrost, and between the inner wall of the buried casing and the evaporator.
[0012] Furthermore, the medium pipeline uses a copper pipe with a diameter of 8mm, a wall thickness of 1.0mm, and an inner diameter of 6.0mm; the throttle uses a copper pipe with an outer diameter of 1.8mm, a wall thickness of 0.5mm, and an inner diameter of 0.8mm; the evaporator is made of a copper pipe with an outer diameter of 6mm and an inner diameter of 4.8mm; the buried sleeve is made of 201 stainless steel pipe with a wall thickness of 1.5mm; and the mortar backfill uses cement-based thermally conductive mortar.
[0013] Furthermore, the cabinet includes a chassis and a base at its bottom. The chassis has an upper support plate and a lower support plate inside. The upper support plate is equipped with a frequency converter, a DC compressor, a condenser, a liquid receiver dryer, and a throttle. The lower support plate is equipped with a battery and a charge / discharge controller.
[0014] Furthermore, the base is a columnar structure with a height of 40-80cm; air vents are provided on both sides of the chassis.
[0015] Furthermore, the cooling unit is located within the permafrost layer or in the active layer above the permafrost layer; the cooling unit is horizontally arranged 30-50cm below the ground surface, or buried at the interface between the ground surface and the structure.
[0016] Furthermore, the cooling units are spaced apart on the ground surface above the permafrost foundation on both sides of the linear engineering structure; or, the cooling units are spaced apart on the ground surface around the point-like engineering structure.
[0017] The technological advancements achieved by this invention compared to existing technologies are as follows: This invention adopts a "solar and wind power - DC power supply - refrigeration cycle" technical approach. It generates electricity through photovoltaic power generation equipment and wind turbines, stores the electrical energy in batteries, and uses this energy to drive a DC compressor in a refrigeration unit. The refrigeration unit then cools the permafrost through a cooling unit located in the foundation. This scheme uses off-grid photovoltaic and wind power generation to directly drive a DC brushless electric compressor, which in turn drives vapor compression refrigeration to circulate and deliver the cold energy to the permafrost layer. Compared to the conventional "solar and wind power - DC power supply - AC power supply - refrigeration cycle" approach, it omits the DC-AC power inverter stage, eliminating energy loss in that stage. It also offers advantages such as low current surge, low power consumption, and high temperature control accuracy, solving the power supply problem and the issues of high starting current and high energy consumption during permafrost protection. Attached Figure Description
[0018] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.
[0019] In the attached diagram: Figure 1 A schematic diagram of an off-grid DC refrigeration device for protecting permafrost, provided for an embodiment of this utility model; Figure 2 This is a schematic diagram of the chassis structure in an embodiment of the present utility model; Figure 3 This is a schematic diagram of the base structure in an embodiment of the present utility model; Figure 4 This is a layout diagram of the inside of the chassis and a schematic diagram of the internal structure of the cooling unit in an embodiment of this utility model; Figure 5 This is a schematic diagram of the structure of the refrigeration unit in an embodiment of the present invention; Figure 6 This is a schematic diagram showing the wire connections of the battery, charge / discharge controller, frequency converter, and DC compressor in an embodiment of this utility model. Figure 7 This is an application state diagram of one embodiment of the present invention; Figure 8 This is an application state diagram of another embodiment of the present invention; Figure 9 for Figure 8 A schematic diagram of the layout of the off-grid DC refrigeration unit around the foundation; In the picture: 1-Rack, 101-Chassis, 102-Base, 103-Air vent, 104-Upper support plate, 105-Lower support plate; 2-Battery; 3-Charge / discharge controller; 4-Inverter; 5-DC compressor; 6-Condenser; 7-Throttle device; 8-Liquid receiver dryer; 9-Evaporator; 10-Media pipeline; 11-Foundation, 1101-Active layer, 1102-Permafrost layer; 12-Buried sleeve; 13-Roadbed; 14-Foundation. Detailed Implementation
[0020] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this utility model will be described below with reference to the accompanying drawings.
[0021] like Figure 1 , Figure 4 As shown, this utility model provides an off-grid DC refrigeration device for protecting permafrost, including an off-grid power supply unit, a refrigeration unit, and a cooling transmission unit placed within the permafrost. The off-grid power supply unit includes a photovoltaic power generation device, a wind turbine, a battery 2, a charge / discharge controller 3, and a frequency converter 4. The photovoltaic power generation device and the wind turbine are electrically connected to the battery 2. The battery 2 is electrically connected to the refrigeration unit, and the refrigeration unit is connected to the cooling transmission unit, which is used to refrigerate the permafrost. Figure 6 As shown, the photovoltaic power generation equipment and the wind turbine are connected in parallel to the input electrode of the charge-discharge controller 3. The energy storage electrode of the charge-discharge controller 3 is connected to the battery 2. The output electrode of the charge-discharge controller 3 is connected to the input of the frequency converter 4. The output of the frequency converter 4 is connected to the DC compressor 5 of the refrigeration unit.
[0022] During installation, the photovoltaic power generation equipment and wind turbine (not shown in the figure) are mounted on a column (not shown in the figure). The wind turbine is mounted at the top of the column, and the photovoltaic modules of the photovoltaic power generation equipment are mounted in the upper middle part of the column. The installation tilt angle of the photovoltaic modules is 60° to prevent dust accumulation. Preferably, the column height is 3.0m, the photovoltaic modules are fixed to the column at a height of 2.0m by clamps, and the wind turbine is fixed to the top of the column by flanges.
[0023] The selection of off-grid power supply units is as follows: The photovoltaic modules are selected as monocrystalline silicon photovoltaic modules in order to improve photoelectric conversion efficiency, reduce space occupation, and improve adaptability to scenarios where space is limited on the side of traffic lines.
[0024] The wind turbine is a vertical axis wind turbine, which has the advantages of being wind-insensitive, able to start generating electricity in low wind conditions, and safe and stable in high wind speed conditions. Its beneficial effect is that it can adapt to the strong winds of the Qinghai-Tibet Plateau, ensuring its service life. Preferably, the wind turbine has a power of 500W.
[0025] The battery is a gel battery, designed to maintain normal charge and discharge capacity in the -30℃ low-temperature weather of the Qinghai-Tibet Plateau. Preferably, two 12V 40Ah gel batteries are selected.
[0026] The functions of the charge / discharge controller are, firstly, to prevent the battery from being overcharged or over-discharged, thus extending its service life; and secondly, to adjust the power supply mode, that is, to preset or remotely and dynamically adjust the power supply switching time period according to the permafrost cooling requirements and the continuous operation time limit of the DC compressor.
[0027] The inverter's function is to output a variable voltage DC power supply, which adjusts the speed of the DC compressor by changing the voltage of the DC power supply, adapting to the cooling capacity requirements and electrical load of the refrigeration unit.
[0028] In a specific embodiment of this utility model, the refrigeration unit includes a DC compressor 5, a condenser 6, a liquid receiver dryer 8, a throttle valve 7, and an evaporator 9. The DC compressor 5, condenser 6, liquid receiver dryer 8, throttle valve 7, evaporator 9, and DC compressor 5 are sequentially connected through a medium pipeline 10 to form a closed loop, and the closed loop is filled with refrigerant. The DC compressor 5, condenser 6, liquid receiver dryer 8, and throttle valve 7 are disposed inside the cabinet 1, and the evaporator 9 is disposed inside the cooling unit.
[0029] The selection scheme for the refrigeration unit is as follows: The DC compressor is a brushless DC electric compressor, the core drive component of the refrigeration equipment. It is connected to the power supply via a frequency converter. The function of the DC electric compressor is to draw refrigerant vapor from the evaporator and rapidly increase the temperature and pressure of the refrigerant through mechanical compression. The purpose of using a brushless DC compressor is to regulate the cooling capacity through stepless speed control, avoiding current surges and temperature fluctuations caused by frequent start-stop cycles, and maintaining stable cooling efficiency. Compared to conventional AC electric compressors used in industrial and civil applications, the advantages of using the brushless DC electric compressor are: First, off-grid photovoltaic and wind turbine generators both produce DC power, which can directly drive the compressor, thus eliminating the need for inverters and other DC-AC conversion components, reducing equipment investment and losses in the power conversion process. Second, the DC electric compressor has better starting and braking performance, with a lower starting current surge than AC electric compressors, and the DC voltage is more stable than the AC voltage, resulting in more stable operation of the refrigeration equipment. Third, during operation, DC electric compressors consume relatively little electricity and can automatically and precisely adjust speed over a wide range according to the refrigerant cycle load via a frequency converter, avoiding excessive light-load and overload losses and achieving a higher energy efficiency ratio. Fourth, by eliminating brushes, DC compressors experience less mechanical wear during operation, resulting in a longer service life and making them more suitable for the harsh climate of permafrost regions in high-altitude areas and the vibration environment along transportation routes.
[0030] Preferably, the DC compressor is a brushless DC electric compressor with a rated power of 24V and an input power of 150W±10%. The advantages of a rated voltage of 24V are: first, it is equal to the generation voltage of currently commercial photovoltaic and wind power generation components, and it is easy to adapt to commercial batteries (rated voltage range of 2-24V) through series and parallel connection, reducing the power loss of secondary voltage conversion and achieving high energy utilization; second, it facilitates overload and overvoltage protection, has high output stability, and ensures high safety for equipment and personnel.
[0031] The condenser is a cubic finned tube condenser that relies on natural air convection for cooling. Its function is to release heat and condense the high-pressure superheated refrigerant vapor at the condensation temperature. Preferably, the condenser has a heat dissipation capacity of 300W.
[0032] The liquid storage dryer is a general-purpose valveless molecular sieve liquid storage dryer, which is used to store refrigerant, perform liquid-gas separation of refrigerant, absorb water and filter it, so as to ensure the normal operation and efficient operation of the refrigeration unit.
[0033] The throttling device is a capillary tube, which is a copper tube with a length of 1.2m, an outer diameter of 1.8mm, a wall thickness of 0.5mm, and an inner diameter of 0.8mm. Its function is to intercept, slow down, and reduce the pressure of the liquid refrigerant, so that it changes from a liquid state to a gas-liquid two-phase mixture.
[0034] The refrigerant selected is R134a, R404a, etc., which have an evaporation pressure greater than atmospheric pressure (101.1 kPa). On the one hand, the refrigeration temperature is below 0℃, which can effectively cool the permafrost. On the other hand, the refrigerant is always under positive pressure to prevent air from seeping in and affecting the purity of the refrigerant.
[0035] The medium pipeline 10 uses a copper tube with a diameter of 8 mm, a wall thickness of 1.0 mm, and an inner diameter of 6.0 mm to reduce the flow resistance of the refrigerant between components. The evaporator 9 is made of a copper tube with an outer diameter of 6 mm and an inner diameter of 4.8 mm. The spiral section of the evaporator causes the refrigerant gas-liquid mixture to absorb heat and boil, turning it into vapor and generating a cooling effect. Preferably, the length of the evaporator copper tube is 25 m, and the corresponding refrigerant charge is 200 g.
[0036] As a preferred structure, the cooling unit includes a buried sleeve 12 and mortar backfill material. The evaporator 9 is disposed inside the buried sleeve 12. The evaporator 9 is divided into a straight section and a spiral section, and both the straight section and the spiral section are disposed inside the buried sleeve 12. The mortar backfill material is filled between the buried sleeve 12 and the permafrost, and between the inner wall of the buried sleeve 12 and the evaporator 9.
[0037] In specific manufacturing, the buried sleeve 12 is made of 201 stainless steel with a wall thickness of 1.5mm, and the pipe diameter can be selected as 76mm, 89mm, 102mm, 114mm, or 133mm. Its function is to protect the evaporator from pressure damage and corrosion under buried conditions. The structural form of the buried sleeve is designed as a straight pipe or a bent pipe according to the actual scenario.
[0038] The mortar backfill material is made of cement-based thermally conductive mortar, which is used to fill the gaps between the outer wall of the buried casing and the permafrost, and between the inside of the buried casing and the evaporator. Its function is to improve the cold energy path between the evaporator, the buried casing and the permafrost, form a cold bridge and prevent the accumulation and loss of cold energy.
[0039] In specific embodiments of this utility model, such as Figure 1-4 As shown, the cabinet 1 includes a chassis 101 and a base 102 at its bottom. The chassis 101 has an upper support plate 104 and a lower support plate 105 inside. The upper support plate 104 is equipped with a frequency converter 4, a DC compressor 5, a condenser 6, a liquid receiver dryer 8, and a throttle 7. The lower support plate 105 is equipped with a battery 2 and a charge / discharge controller 3. The base 102 has a columnar structure, and the chassis 101 is fixed to the top of the base 102 by bolts.
[0040] The chassis 101 has air vents 103 on both sides of its side walls. The purpose of this is to enhance air convection in the upper space of the chassis, which on the one hand ensures the cooling and liquefaction effect of the gaseous refrigerant inside the condenser, and on the other hand avoids high temperatures inside the chassis in summer, and improves the working condition of electrical components such as DC compressor, battery, charge and discharge controller, and filter.
[0041] In specific manufacturing, the chassis is a rainproof stainless steel chassis with dimensions of 50cm high * 40cm long * 30cm wide. The space above the upper support plate 104 and the lower support plate 105 is 25cm high. The height of the base 102 is 40-80cm, determined according to the maximum water accumulation height on the ground surface by 30cm, in order to prevent surface water from submerging the refrigeration unit and other electrical equipment.
[0042] The refrigeration unit and the cooling supply unit are connected as follows: the outlet of the DC compressor 5 is connected to the inlet of the condenser 6; the outlet of the condenser 6 is connected to the inlet of the liquid receiver-dryer 8; the outlet of the liquid receiver-dryer 8 is connected to the inlet of the expansion joint 7; the outlet of the expansion joint 7 is connected to the inlet of the evaporator 9; and the outlet of the evaporator 9 is connected to the inlet of the DC compressor 5. Figure 5 As shown, the DC compressor, condenser, receiver-dryer, throttle, and evaporator form a closed loop connected in sequence, and the refrigerant circulates within the loop.
[0043] The working principles of the above-mentioned refrigeration unit and cooling supply unit are as follows: After the DC compressor is powered on and started, it first draws in the gaseous refrigerant from the evaporator and compresses it into a high-pressure gas, marking the beginning of the entire refrigeration process. Subsequently, driven by the exhaust of the DC compressor, the high-pressure gaseous refrigerant enters the condenser, where it releases heat through heat exchange with the surrounding air and gradually condenses into a liquid state. Next, the liquid refrigerant flows into the receiver-drier, and some of it flows out into the expansion joint under pressure differential. As the refrigerant passes through the expansion joint, it undergoes a pressure reduction and ejection effect, lowering its temperature and causing some to vaporize. The refrigerant exiting the expansion joint forms a gas-liquid mixture. Finally, this low-pressure refrigerant enters the evaporator, absorbs heat from the surrounding permafrost, and evaporates into a gaseous state, thus cooling the permafrost. This complete workflow is continuously repeated, producing a sustained and efficient refrigeration effect.
[0044] When refrigeration units and cooling supply units are arranged on site, they should be placed as close as possible to minimize the length of the connecting pipes between them to prevent loss of cooling capacity along the pipeline.
[0045] The installation scheme for the cooling unit is as follows: The cooling unit can be placed either within the permafrost layer 1102 or within the active layer 1101 above it. It can be installed vertically, horizontally, or inclined, allowing for flexible design. When there are no structures above the surface, it can be installed horizontally, by manually or mechanically excavating trenches to a depth of 30-50cm below the surface. When there are structures such as embankments above the surface, it can be installed at the interface between the surface and the structure by drilling. The purpose of this installation method is to form a thermal barrier layer below the surface, preventing atmospheric heat from transferring downwards to the permafrost layer and causing warming and degradation, while actively outputting and transferring cooling energy to the permafrost layer for cooling. The beneficial effects of a burial depth of 30-50cm also include preventing heat loss when the cooling unit is directly on the surface and maintaining a certain distance from the upper limit of the permafrost layer to prevent thermal disturbance to the permafrost layer during trenching or drilling.
[0046] The arrangement of the cooling units is as follows: a distributed arrangement is adopted, that is, they are arranged at certain intervals on the surface above the permafrost foundation to be protected. For example... Figure 7 As shown, when used to protect the permafrost foundation beneath linear engineering structures such as roadbeds and oil pipelines, the cooling units are evenly distributed along the longitudinal direction of the line on both sides; for example... Figure 8 , 9 As shown, when used to protect point-like engineering structures such as pile foundations, bridge abutments, and power tower foundations, the cooling units are evenly arranged around the perimeter of the foundation on the ground surface.
[0047] The rack layout is as follows: Based on the location of the buried sleeve's end, place it on the ground nearby, first installing the column-type base to ensure its stability, level bottom, and vertical column. Then install the chassis on the upper end of the column-type base.
[0048] The arrangement scheme for off-grid power supply units is as follows: when site conditions permit, they should be arranged near the surface cooling unit; when site conditions do not permit, such as when there are no moving mechanical parts of wind turbines along the railway line, or when the terrain is low and affects photovoltaic power generation, they should be arranged in a location with suitable installation conditions. In this case, the connection circuit between the off-grid power supply unit and the cooling unit should be strengthened to prevent leakage hazards.
[0049] In summary, this utility model has the following beneficial effects: First, adopting a DC brushless electric compressor drive scheme can reduce the starting current surge, reduce operating power consumption, improve operating stability, reduce the configuration capacity of photovoltaic and wind turbine generator sets and inverter components, and improve the economy and energy efficiency of permafrost cooling protection technology.
[0050] Secondly, by adding air vents on both sides of the chassis, the high wind speed at high altitudes is fully utilized to enhance the energy-saving solution of cooling the condenser inside the chassis through natural air convection. This eliminates the conventional practice of using electric fans for forced convection cooling of condensers, thus reducing power consumption.
[0051] Third, a scheme for horizontally or inclinedly burying the cooling components in the active layer of permafrost is proposed, so that they can play the role of "thermal barrier layer" as the main function and "active cooling" as the auxiliary function. Under the premise of controlling the thermal erosion of permafrost by the climate environment, the active supplementation of cooling capacity is more energy-efficient and can avoid the secondary risk of thermal disturbance when the cooling components are directly embedded in the permafrost layer.
[0052] Fourth, a distributed layout scheme for the cooling units is proposed. Depending on the scenario requirements, the units can be designed in a longitudinally or circumferentially uniform distribution, ensuring the uniformity of permafrost protection and improving the adaptability of the refrigeration equipment to different types of sites. This invention's refrigeration system offers technical advantages such as high utilization of photovoltaic and wind power generation, low starting current impact on the refrigeration equipment, energy saving during operation, and good scenario adaptability, achieving the dual goals of permafrost protection and energy conservation.
[0053] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of the claims of this utility model.
Claims
1. An off-grid DC refrigeration device for protecting permafrost, characterized in that: It includes an off-grid power supply unit, a refrigeration unit, and a cooling transmission unit placed in permafrost; the off-grid power supply unit includes a photovoltaic power generation device, a wind turbine, a battery, a charge / discharge controller, and a frequency converter, and the photovoltaic power generation device and the wind turbine are electrically connected to the battery; the battery is electrically connected to the DC compressor of the refrigeration unit, and the refrigeration unit is connected to the cooling transmission unit, which is used to refrigerate the permafrost.
2. The off-grid DC refrigeration device for protecting permafrost according to claim 1, characterized in that: The photovoltaic power generation equipment and the wind turbine are connected in parallel to the input electrode of the charge-discharge controller. The energy storage electrode of the charge-discharge controller is connected to the battery. The output electrode of the charge-discharge controller is connected to the input of the frequency converter. The output of the frequency converter is connected to the DC compressor of the refrigeration unit.
3. An off-grid DC refrigeration device for protecting permafrost according to claim 2, characterized in that: The photovoltaic power generation equipment and wind turbine are mounted on a column, with the wind turbine mounted on the top of the column and the photovoltaic modules of the photovoltaic power generation equipment mounted on the upper middle part of the column.
4. An off-grid DC refrigeration device for protecting permafrost according to claim 2, characterized in that: The refrigeration unit includes a DC compressor, a condenser, a liquid receiver dryer, a throttle valve, and an evaporator. The DC compressor, condenser, liquid receiver dryer, throttle valve, and evaporator are sequentially connected through a medium pipeline to form a closed loop, which is filled with refrigerant. The DC compressor, condenser, liquid receiver dryer, and throttle valve are located inside a cabinet, while the evaporator is located inside the cooling unit.
5. An off-grid DC refrigeration device for protecting permafrost according to claim 4, characterized in that: The cooling unit includes a buried casing and mortar backfill material. The evaporator is installed inside the buried casing. The evaporator is divided into a straight section and a spiral section, and both the straight section and the spiral section are installed inside the buried casing. The mortar backfill material is filled between the buried casing and the permafrost, and between the inner wall of the buried casing and the evaporator.
6. An off-grid DC refrigeration device for protecting permafrost according to claim 5, characterized in that: The medium pipeline uses copper pipe with a diameter of 8mm, a wall thickness of 1.0mm, and an inner diameter of 6.0mm; the throttle uses copper pipe with an outer diameter of 1.8mm, a wall thickness of 0.5mm, and an inner diameter of 0.8mm; the evaporator is made of copper pipe with an outer diameter of 6mm and an inner diameter of 4.8mm; the buried sleeve is made of 201 stainless steel pipe with a wall thickness of 1.5mm; and the mortar backfill uses cement-based thermally conductive mortar.
7. An off-grid DC refrigeration device for protecting permafrost according to claim 4, characterized in that: The cabinet includes a chassis and a base at its bottom. The chassis has an upper support plate and a lower support plate inside. The upper support plate is equipped with a frequency converter, a DC compressor, a condenser, a liquid receiver dryer, and a throttle. The lower support plate is equipped with a battery and a charge / discharge controller.
8. An off-grid DC refrigeration device for protecting permafrost according to claim 7, characterized in that: The base is a columnar structure with a height of 40-80cm; air vents are provided on both sides of the chassis.
9. An off-grid DC refrigeration device for protecting permafrost according to claim 5, characterized in that: The cooling unit is located within the permafrost layer or in the active layer above the permafrost layer; the cooling unit is horizontally arranged 30-50cm below the ground surface, or buried at the interface between the ground surface and the structure.
10. An off-grid DC refrigeration device for protecting permafrost according to claim 9, characterized in that: The cooling units are spaced apart on the ground surface above the permafrost foundation on both sides of the linear engineering structure; or, the cooling units are spaced apart on the ground surface around the point-shaped engineering structure.