Heat pump system for preventing and controlling frost heaving disease of roadbed in cold region and design method of heat pump system

Abstract

The invention discloses a heat pump system for preventing and controlling frost heaving diseases of a roadbed in a cold region and a design method of the heat pump system, and belongs to the technical field of maintenance of traffic infrastructures in the cold region. The wind energy capturing unit captures wind energy, converts the wind energy into mechanical energy, stores the mechanical energy in the flywheel energy storage unit and then drives the heat energy conversion unit, and the heat energy conversion unit collects low-grade renewable heat energy, converts the low-grade renewable heat energy into high-grade heat energy and conveys heat to the frost heaving disease part of the roadbed; a heat pump system is designed, the manufacturing cost is reduced, and the conversion efficiency is improved; shallow ground temperature energy in a foundation is used as a main heat source, wind energy is used for providing driving force, and the resource advantages of high wind speed and stable ground temperature energy reserve in winter are fully utilized; the flywheel energy storage unit is used for stabilizing and filtering the volatility of wind energy, and mechanical energy overflowing when the wind speed is high is stored for being output when the wind speed is low, so that the effect of peak load shifting is achieved.

Description

Technical Field

[0001] This invention belongs to the field of cold region transportation infrastructure maintenance technology, and specifically relates to a heat pump system and its design method for preventing and controlling frost heave disease of roadbeds in cold regions. Background Technology

[0002] Frost heave is a common problem in railway and highway engineering in cold regions, accompanied by other issues such as mud pumping, track bed and pavement subsidence, and outward extrusion. It is a key factor restricting the operational quality of high-speed railways and highways in cold regions. The cause of frost heave is the freezing and expansion of moisture in the sub-zero temperatures of winter. During freezing, the redistribution of moisture leads to ice accumulation, causing uneven bulging of the roadbed surface. Traditional frost damage control measures include soil improvement, drainage, and insulation. However, for severely affected areas, these measures are limited by the inability to actively control the roadbed temperature, resulting in poor timeliness. Furthermore, traditional measures involve numerous procedures and are time-consuming, primarily implemented during the construction phase. Once operational, the limited number and short duration of maintenance windows for high-speed railways exacerbate the problem, leading to long implementation cycles and high costs in manpower and resources. Therefore, developing fast-implementing, proactive, and timely frost damage control measures is crucial for improving the construction and operation quality of high-grade transportation infrastructure in cold regions.

[0003] The sub-zero temperatures of the roadbed in winter are a key cause of frost damage. Therefore, the engineering industry has begun developing heating measures that can actively input heat into the roadbed and raise its temperature. Analysis shows that the heating load on the roadbed is lower than that of building air conditioning, but frost heave is characterized by a dispersed distribution. Since transportation routes generally lack heating pipe networks and power grids, the selection of heat sources is crucial. Conventional heat sources all face certain difficulties, including the need for manual operation of fuel boilers; the large power load of electric heat tracing, which does not conform to the scientific energy use principle of "temperature matching and tiered utilization"; and the large reserves and wide distribution of renewable thermal energy such as geothermal energy and solar energy, but their heat flux density and temperature are too low. A heat pump is a heat-lifting device, and the utilization technology of renewable thermal energy based on heat pumps is a reasonable way to actively heat the roadbed and prevent frost heave. For example, application number CN202411085190.1 discloses a thermal energy conversion device that uses a heat pump as the conversion carrier, electricity as the driving source (electric energy-mechanical energy), and geothermal energy, air energy, and solar energy as the main heat sources. The technical advantages of heat pumps are high heating quality and low energy consumption. However, the problem is that heat pumps still require electricity to drive them. Given the lack of grid power supply along transportation routes, off-grid photovoltaic / wind power supply is often used. The difficulties and risks include: (1) High loss rate in the DC-AC conversion process of electricity. In addition, the intermittent nature of solar radiation and the differences between winter and summer require increased capacity of power generation components and supporting energy storage equipment. The cost of power supply equipment is sometimes even higher than that of heat pumps, resulting in poor economic efficiency; (2) Photovoltaic power supply components installed along transportation routes pose a risk of leakage, which is a source of risk to railway track circuits and other signal equipment and traffic safety; (3) The service life of photovoltaic components does not match that of heat pumps, leading to a year-by-year decrease in power generation efficiency and the need to replace photovoltaic components midway. In summary, the current solar / wind energy-electric energy-mechanical energy-thermal energy conversion process of roadside heat pumps involves many stages and has a high energy loss rate, which is not conducive to large-scale promotion.

[0004] It is evident that the development trend of active heating measures for roadbed frost heave in cold regions is to shift away from traditional electric power-driven methods. In fact, compared to other types of renewable energy, wind energy is more widely and stably distributed in nature. Cold regions are the main areas of roadbed frost heave distribution and also areas rich in wind energy, with high wind speeds in winter and wind power densities generally ranging from 200 to 300 W / m². 2 The above demonstrates good seasonal compatibility with the needs of roadbed frost damage prevention. The energy loss rate when the kinetic energy contained in airflow is directly converted into mechanical energy is very low, and the economic cost of wind energy utilization is relatively lower than that of solar energy; these are the main advantages of wind energy resources. Therefore, one way to improve roadbed heat pump anti-frost heave technology is to develop a heat pump system directly driven by wind energy. Summary of the Invention

[0005] To address the above problems, this invention provides a heat pump system and its design method for preventing and controlling frost heave disease in roadbeds in cold regions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A heat pump system for preventing frost heave disease in roadbeds in cold regions is disclosed. The heat pump system includes a wind energy capture unit, a flywheel energy storage unit, and a thermal energy conversion unit. The output end of the wind energy capture unit is connected to the input end of the flywheel energy storage unit, and the output end of the flywheel energy storage unit is connected to the input end of the thermal energy conversion unit. The wind energy capture unit captures wind energy, converts it into mechanical energy, and stores it in the flywheel energy storage unit. The flywheel energy storage unit drives the thermal energy conversion unit. The thermal energy conversion unit collects low-grade renewable thermal energy and converts it into high-grade thermal energy to deliver heat to the frost heave-affected parts of the roadbed and raise their temperature.

[0008] Furthermore, the heat energy conversion unit includes a compressor, a condenser, a liquid receiver, a dryer filter, a throttle valve, and an evaporator. The exhaust port of the compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the liquid receiver, the outlet of the liquid receiver is connected to the inlet of the dryer filter, the outlet of the dryer filter is connected to the inlet of the throttle valve, the outlet of the throttle valve is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the return port of the compressor, thereby forming a closed loop internally filled with heat transfer fluid.

[0009] The storage tank is used to store the liquid heat transfer fluid and regulate its flow rate to the throttle.

[0010] The evaporator is located in the foundation at a distance of 400cm from the toe of the roadbed slope in order to prevent the heat absorption and cooling zone of the foundation from spreading to the roadbed. On the cross section of the roadbed, the condenser is located at 1 / 3 of the maximum vertical freezing depth of the roadbed frost heave layer.

[0011] Furthermore, the compressor has a rated speed range of 600-1000 r / min and a rated torque range of 50-100 N·m; the dryer filter is a molecular sieve filter, and the throttling device is a capillary tube.

[0012] The evaporator is made of copper tube with an outer diameter of 8 mm, a wall thickness of 0.6 mm, and an inner diameter of 6.8 mm. The condenser is made of copper tube with an outer diameter of 6 mm, a wall thickness of 0.6 mm, and an inner diameter of 4.8 mm. Both the evaporator and the condenser are spiral columns. Both the evaporator and the condenser are equipped with buried sleeves.

[0013] Furthermore, the heat transfer medium is R134a, and the evaporation temperature range of R134a is -10 to -25°C, and the condensation temperature range is 40 to 60°C.

[0014] Furthermore, the compressor, liquid storage tank, dryer filter, and throttling device of the flywheel energy storage unit and the thermal energy conversion unit are all installed inside the cabinet, and the wind energy capture unit is installed on the top of the outside of the cabinet. The cabinet is installed on the foundation on the side of the roadbed. Multiple heat pump systems are arranged at intervals along the longitudinal length of the roadbed according to the frost heave disease, and the distance between two adjacent heat pump systems is 2.0m-4.0m.

[0015] Furthermore, the cabinet is equipped with an upper tray and a lower tray inside, and guide rails that mate with the upper tray and the lower tray are respectively provided on the inner walls of both sides of the cabinet; the flywheel energy storage unit is set on the upper tray, and the compressor, liquid storage tank, dryer filter and throttle are all set on the lower tray; the bottom of both sides of the cabinet is provided with connecting ports for pipelines connecting the condenser and the evaporator to pass through, and the outside of the connecting ports is equipped with dust covers.

[0016] Furthermore, the wind energy capture unit includes a wind turbine and its lower shaft. The wind turbine includes a hub and multiple blades, which are radially evenly distributed around the hub. The shaft is located at the lower end of the hub and is mounted on the top of the cabinet via a tower. The lower end of the shaft passes through the tower and the top wall of the cabinet and is connected to the low-speed input shaft of the gearbox I. The high-speed output shaft of the gearbox I is connected to the flywheel energy storage unit. The transmission ratio of the gearbox I is 1:15.

[0017] Furthermore, the flywheel energy storage unit includes a vacuum chamber and a flywheel. The flywheel is disposed in the vacuum chamber. The input shaft of the flywheel passes through the upper wall of the vacuum chamber and is connected to the high-speed output shaft of the transmission gearbox I. The output shaft of the flywheel passes through the lower wall of the vacuum chamber and is connected to the transmission gearbox II. The input shaft and output shaft of the flywheel are respectively connected to the upper and lower walls of the vacuum chamber through bearings.

[0018] Furthermore, the vacuum chamber is a cylindrical container with a diameter of 45cm and a height of 15cm; the flywheel has a diameter of 40cm and is made of lightweight, high-strength material; and the bearing is an air bearing.

[0019] This invention also provides a design method for the above-mentioned heat pump system, the design of which includes the following steps:

[0020] Step 1: Determine the compressor model based on the roadbed heat load;

[0021] The compressor's parameters include its rated speed (w). c (r / min), moment of inertia J c (kg·m²), rated shaft power P c (W), Rated Torque T c (N·m); The starting torque T0 of the compressor is generally equal to the rated torque T. c 2 times.

[0022] Step 2: Design the flywheel according to the compressor drive requirements;

[0023] The parameters of a flywheel include its moment of inertia J. f Speed ​​range w f Geometric dimensions and flywheel mass m f The geometric dimensions include the radius R and thickness D of the flywheel;

[0024] (21) Calculate the energy E that the flywheel needs to store. f The calculation method is as follows:

[0025] (1)

[0026] In the formula, E f The energy required to store by the flywheel, J; J c η is the compressor's moment of inertia, kg·m²; η1 is the flywheel's transmission efficiency; w c P is the compressor's rated speed, in r / min; c t is the rated shaft power of the compressor, in W; t is the duration for which the flywheel keeps the compressor running without airflow, in s;

[0027] (22) Based on the energy E that the flywheel needs to store f Choose the flywheel material and determine the design speed range (w). f =[w min w max Calculate the mass m of the flywheel. f The calculation method is as follows:

[0028] (2)

[0029] In the formula, ω max For the maximum design speed w max The corresponding maximum angular velocity, rad / s; ω min For the minimum design speed w min The corresponding minimum angular velocity, rad / s; R is the radius of the flywheel, taken as 0.2m; m f The mass of the flywheel is expressed in kg.

[0030] Based on the calculated flywheel mass m f By combining the known flywheel density and flywheel radius, the flywheel thickness D can be calculated.

[0031] (23) Verify the maximum torque T of the flywheel f Does it meet the starting torque T0 required by the compressor? The starting torque T0 of the compressor is its rated torque T. c 2 times;

[0032] (3)

[0033] In the formula, α is the maximum allowable angular deceleration of the flywheel, in rad / s²;

[0034] Such as T f If T ≥ T0, then continue with step 3; if T f If <T0, then the design speed range [w] should be redefined. min w max ], until the flywheel's maximum torque T f The starting torque T0 required by the compressor is greater than or equal to the starting torque required by the compressor.

[0035] Step 3: Calculation and selection of the transmission gearbox II between the compressor and the flywheel;

[0036] The optimal operating speeds of the compressor and flywheel need to be matched through gearbox II; the calculation method for the transmission ratio i of gearbox II is as follows:

[0037] (4)

[0038] Generally, the flywheel is designed to rotate at a speed of w. f Higher than the compressor's rated speed w c Therefore, a gearbox II is needed to reduce the speed, resulting in a corresponding increase in torque. Thus, it is not necessary to re-evaluate the flywheel torque performance. Based on the calculated transmission ratio i, select the appropriate gearbox model. Generally, when i < 5, select a parallel shaft gear; when i ≥ 5, select a planetary gear.

[0039] Step 4: Based on the flywheel design results, calculate and select the wind energy harvesting unit, including the required input power P. w and torque T w ;

[0040] (41) Calculate the power input P required by the flywheel. w Based on the model of gearbox II in step 3, determine the transmission efficiency η2 of gearbox II. η3 is the transmission efficiency of gearbox I (constant speed ratio). The calculation method is as follows:

[0041] (5)

[0042] (42) Calculate the required input rotational speed w of the wind energy capture unit. w and torque T w The calculation method is as follows:

[0043] (6)

[0044] (7)

[0045] (43) Perform torque matching calculations to ensure that the flywheel can be driven. If T w ≥i·T f The requirements are met; if T w <i·T f Then, starting from step 2, the design calculations are re-performed to form the first iterative optimization design process.

[0046] Step 5: Calculate and select the wind turbine in the wind energy capture unit based on the wind energy conditions at the application site.

[0047] (51) Investigate and determine the average winter wind speed v (m / s) of the location, and calculate the radius r of the wind turbine. The calculation method is as follows:

[0048] (8)

[0049] In the formula, C p ρ is the wind energy utilization coefficient; ρ is the air density, kg / m³ 3 .

[0050] (52) Perform speed matching calculation. Under the conditions of local wind speed and rotor radius, the actual rotor speed w0 is:

[0051] (9)

[0052] In the formula, λ is the tip speed ratio of the wind turbine blades.

[0053] If w0 ≥ w w This meets the design requirements; if w0 < w w Starting from step 2, the design calculations are re-performed, forming the second iterative optimization design process.

[0054] The technological advancements achieved by this invention compared to existing technologies are as follows:

[0055] (1) Using wind energy to directly drive the compressor reduces energy conversion losses between wind energy and electricity compared with using electric energy to drive the heat pump, lowers system cost, and improves overall conversion efficiency.

[0056] (2) Using shallow geothermal energy in the foundation as the main heat source and wind energy as the driving force for heat conversion, it makes full use of the resource advantages of high wind speed in winter and stable geothermal energy reserves, which is green and environmentally friendly.

[0057] (3) The wind energy capture unit drives the compressor through the flywheel energy storage unit. The flywheel energy storage unit optimizes the "wind energy-mechanical energy" into "wind energy-mechanical energy-kinetic energy". On the one hand, it smooths and filters the fluctuation of wind energy. On the other hand, it stores the mechanical energy that overflows when the wind speed is high, so that it can be output when the wind speed is low. This allows the compressor to continuously obtain sufficient shaft power, which plays a role in peak shaving and valley filling. In this way, the fluctuation and instability of wind energy itself are overcome, and the stability and continuity of heat pump heating performance are improved. Attached Figure Description

[0058] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0059] In the attached diagram:

[0060] Figure 1 This is a schematic diagram illustrating the application status of a heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions, provided by an embodiment of the present invention.

[0061] Figure 2 for Figure 1 The main view;

[0062] Figure 3 This is a schematic diagram of the heat pump system in an embodiment of the present invention;

[0063] Figure 4 This is a schematic diagram of the wind energy capture unit in an embodiment of the present invention;

[0064] Figure 5 This is a schematic diagram of the flywheel energy storage unit in an embodiment of the present invention;

[0065] Figure 6 This is a schematic diagram showing the connection between the wind energy capture unit and the flywheel energy storage unit in an embodiment of the present invention;

[0066] Figure 7 This is a schematic diagram of the internal layout of the cabinet in an embodiment of the present invention;

[0067] Figure 8 This is a schematic diagram of the connection of the thermal energy conversion unit in an embodiment of the present invention;

[0068] Figure 9 This is a schematic diagram showing the connection of the wind energy capture unit, flywheel energy storage unit, and thermal energy conversion unit in an embodiment of the present invention;

[0069] Figure 10 This is a design flowchart of the heat pump system in an embodiment of the present invention;

[0070] In the diagram: 1-Wind energy capture unit, 2-Flywheel energy storage unit, 3-Thermal energy conversion unit;

[0071] 4-Cabinet, 401-Upper tray, 402-Lower tray, 403-Dust cover; 5-Blade, 6-Hub, 7-Shaft, 8-Tower; 9-Gearbox I, 901-Low-speed input shaft, 902-High-speed output shaft; 10-Flywheel, 1001-Input shaft, 1002-Output shaft; 11-Bearing; 12-Gearbox II, 1201-High-speed input shaft, 1202-Low-speed output shaft; 13-Coupling; 14-Vacuum chamber; 15-Compressor, 1501-Drive shaft, 1502-Return port, 1503-Exhaust port; 16-Condenser, 17-Liquid storage tank, 18-Dryer filter, 19-Throttle valve, 20-Evaporator, 21-Buried casing, 22-Roadbed, 23-Foundation. Detailed Implementation

[0072] 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 the present invention will be described below with reference to the accompanying drawings.

[0073] like Figure 1 , Figure 2 As shown, this embodiment of the invention provides a heat pump system for preventing frost heave disease in roadbeds in cold regions. The heat pump system includes a wind energy capture unit 1, a flywheel energy storage unit 2, and a thermal energy conversion unit 3. The output end of the wind energy capture unit 1 is connected to the input end of the flywheel energy storage unit 2, and the output end of the flywheel energy storage unit 2 is connected to the input end of the thermal energy conversion unit 3. The wind energy capture unit 1 captures wind energy and converts it into mechanical energy, which is then stored in the flywheel energy storage unit 2. The flywheel energy storage unit 2 drives the thermal energy conversion unit 3. The wind energy capture unit 1, the flywheel energy storage unit 2, and the thermal energy conversion unit 3 are integrated together to form a complete set of equipment that is easy to manufacture, transport, install, and apply. The thermal energy conversion unit 3 collects low-grade renewable thermal energy and converts it into high-grade thermal energy to deliver heat to the frost heave disease area of ​​the roadbed 22, thereby raising its temperature.

[0074] In specific embodiments of the present invention, such as Figure 7 , 8 As shown, the heat energy conversion unit 3 includes a compressor 15, a condenser 16, a liquid storage tank 17, a dryer filter 18, a throttle valve 19, and an evaporator 20. The exhaust port 1503 of the compressor 15 is connected to the inlet of the condenser 16, the outlet of the condenser 16 is connected to the inlet of the liquid storage tank 17, the outlet of the liquid storage tank 17 is connected to the inlet of the dryer filter 18, the outlet of the dryer filter 18 is connected to the inlet of the throttle valve 19, the outlet of the throttle valve 19 is connected to the inlet of the evaporator 20, and the outlet of the evaporator 20 is connected to the return port 1502 of the compressor 15, thereby forming a closed loop internally filled with heat transfer fluid.

[0075] The liquid storage tank 17 is used to store the liquid heat transfer agent and regulate its flow rate to the throttle 19; the evaporator 20 is arranged in the foundation 23 at a distance of 400cm from the toe of the roadbed 22, in order to prevent the heat absorption and cooling zone of the foundation 23 from spreading to the roadbed 22; on the cross section of the roadbed 22, the condenser 16 is arranged at 1 / 3 of the maximum vertical freezing depth of the frost heave layer of the roadbed 22, because the frost heave deformation of the roadbed mainly occurs in the shallow frost heave zone, and the purpose is to preferentially transfer heat to the shallow frost heave zone. On the one hand, the heat transfer raises the overall temperature of the roadbed, and on the other hand, a cold barrier layer is formed through heat diffusion to prevent the diffusion of atmospheric cold to the deeper parts of the roadbed, thereby reducing the actual freezing depth.

[0076] The compressor 15 is the power source for heat energy conversion. It is a mechanical compressor, including a compression chamber and its internal drive shaft 1501 and swashplate piston (not shown in the figure). One end of the drive shaft 1501 is connected to the swashplate piston, and the other end extends to the outside of the compression chamber and is connected to the flywheel energy storage unit 2. The compression chamber is equipped with a return port 1502 and an exhaust port 1503. The working principle is that the rotation of the drive shaft drives the reciprocating motion of the swashplate piston, which sequentially generates suction and compression effects inside the compression chamber. When the suction effect is generated, it plays a role in drawing in low-temperature, low-pressure gaseous heat transfer fluid; when the compression effect is generated, it plays a role in converting the low-temperature, low-pressure gaseous heat transfer fluid into a high-temperature, high-pressure state, creating conditions for the subsequent release of heat to the roadbed to generate a heating effect.

[0077] In its specific design, the compressor 15 has a rated speed range of 600-1000 r / min and a rated torque range of 50-100 N·m, in order to match the speed / torque combination of the wind turbine and the speed-increasing gearbox. The dryer filter 18 is a molecular sieve filter, and the throttling device 19 is a capillary tube made of a copper tube with an outer diameter of 1.8 mm, a wall thickness of 0.2 mm, an inner diameter of 1.4 mm, and a length of 1.2 m.

[0078] The evaporator 20 is made of a copper tube with an outer diameter of 8 mm, a wall thickness of 0.6 mm, an inner diameter of 6.8 mm, and a length of 25 m. The condenser 16 is made of a copper tube with an outer diameter of 6 mm, a wall thickness of 0.6 mm, an inner diameter of 4.8 mm, and a length of 40 m. Both the condenser 16 and the evaporator 20 are spiral columns. The purpose of making the evaporator tube diameter larger than the condenser tube diameter is twofold: firstly, by increasing the evaporator tube diameter, the pressure drop of the heat transfer fluid is reduced, the evaporation temperature difference between the evaporator inlet and outlet is reduced, and the vaporization efficiency of the heat transfer fluid is improved, thereby increasing the efficiency of collecting geothermal energy; secondly, by reducing the condenser tube diameter, the transport path distance of the heat transfer fluid is increased, the condensation temperature difference between the condenser inlet and outlet is increased, ensuring that the gaseous heat transfer fluid can be completely liquefied, increasing the heat dissipation along the path, thereby improving the heating effect of the roadbed.

[0079] Meanwhile, both the condenser 16 and the evaporator 20 are fitted with buried sleeves 21. The buried sleeves 21 are made of 201 stainless steel and their function is to protect the evaporator embedded in the foundation and the condenser buried in the roadbed, preventing damage from external forces and erosion by soil moisture and chemicals. The evaporator and condenser are fabricated on-site to flexibly adapt to the distribution range of roadbed frost heave and ground temperature distribution conditions, thereby overcoming the difficulty of transportation when the length is too large. The condenser and evaporator are installed by drilling holes with a drilling rig, first inserting the buried sleeves, and then inserting the condenser and evaporator into the buried sleeves.

[0080] In a specific embodiment of the present invention, the heat transfer agent selected is R134a, which has stable performance and high heat capacity per unit area, and the charge amount is 450g. The evaporation temperature range of R134a is -10 to -25℃, and the condensation temperature range is 40 to 60℃, which is beneficial for achieving efficient collection of geothermal energy and efficient heating of the roadbed frost heave layer.

[0081] The operating principle of the aforementioned thermal energy conversion unit is as follows: Utilizing the reverse Carnot cycle principle, firstly, a low-temperature, low-pressure liquid heat transfer agent absorbs heat (geothermal energy) from the ground in the evaporator and vaporizes into low-pressure steam. Secondly, the heat transfer agent gas is compressed into high-temperature, high-pressure steam in the compressor, raising its corresponding condensation temperature to above the ambient temperature. Then, the high-temperature, high-pressure gas enters the condenser, dissipates heat to the surrounding roadbed frost heave layer, and condenses into high-pressure liquid. Finally, it is throttled through a capillary tube into a low-temperature, low-pressure liquid heat transfer agent, lowering its corresponding evaporation temperature to below the ambient temperature, and then flows back into the evaporator, thus completing one heating cycle. This cycle is repeated continuously to achieve the continuous collection, conversion, and output of geothermal energy. Typically, the coefficient of performance (COP) of a heat pump is between 3 and 5, meaning that a heat pump can convert 3 to 5 units of thermal energy while consuming 1 unit of mechanical energy; essentially, it is a heat-lifting device.

[0082] In specific embodiments of the present invention, such as Figure 3 , 5 As shown in Figures 7 and 9, the compressor 15, liquid storage tank 17, dryer filter 18, and throttling device 19 of the flywheel energy storage unit 2 and the thermal energy conversion unit 3 are all installed inside the cabinet 4. The wind energy capture unit 1 is installed on the top outer side of the cabinet 4. The cabinet 4 is installed on the foundation 23 on the side of the roadbed 22. Multiple heat pump systems are arranged at intervals along the longitudinal length of the roadbed 22 according to the frost heave disease, with the spacing between two adjacent heat pump systems being 2.0m-4.0m. Figure 1 As shown. In practical applications, the number of heat pump systems should be rationally designed based on the longitudinal distribution length of frost heave damage along the roadbed. For short-wave frost heave, one heat pump system should be installed at the peak frost location. For long-wave frost heave, multiple heat pump systems should be evenly installed at certain intervals, with a recommended spacing of 2.0m-4.0m.

[0083] During specific assembly, the rotating shaft 7 of the wind energy capture unit 1, the low-speed input shaft and high-speed output shaft of the gearbox I9, the input shaft and output shaft of the flywheel 10, the high-speed input shaft and low-speed output shaft of the gearbox II12, and the drive shaft of the compressor 15 are all on a straight line, which is located at the exact center of the cabinet 4.

[0084] like Figure 7 As shown, the cabinet 4 has an upper tray 401 and a lower tray 402 inside. The inner walls on both sides of the cabinet 4 are respectively provided with guide rails that cooperate with the upper tray 401 and the lower tray 402. The flywheel energy storage unit 2 is set on the upper tray 401. The compressor 15, liquid storage tank 17, dryer filter 18 and throttle 19 are all set on the lower tray 402. The compressor 15 is placed in the center position, the liquid storage tank 17 is located to the right of the compressor 15, and the dryer filter 18 and throttle 19 are located to the left of the compressor 15. The bottom of both sides of the cabinet 4 are provided with pipe openings for the pipelines connecting the condenser 16 and the evaporator 20 to pass through. The outside of the pipe openings is provided with dust covers 403.

[0085] In its actual manufacturing, the cabinet is a stainless steel cubic chassis, measuring 50cm x 50cm x 60cm (length x width x height). The cabinet is connected using brazing. An upper support plate 401 and a lower support plate 402 divide the interior into upper and lower compartments, with heights of 30cm and 25cm respectively. The lower support plate 402 is 5cm from the bottom of the cabinet for moisture and water protection. The cabinet can be prefabricated in the factory and then transported to the site. The cabinet 4 is positioned at the foot of the slope 22 of the roadbed to minimize heat loss between the cabinet 4 and the condenser 16.

[0086] In specific embodiments of the present invention, such as Figure 3 , 4 As shown in Figure 6, the wind energy capture unit 1 includes a wind turbine and its lower shaft 7. The wind turbine includes a hub 6 and multiple blades 5, which are radially evenly distributed around the hub 6. The shaft 7 is located at the lower end of the hub 6 and is mounted on the top of the cabinet 4 via a tower 8. The lower end of the shaft 7 passes through the tower 8 and the top wall of the cabinet 4 and is connected to the low-speed input shaft 901 of the gearbox I9. The high-speed output shaft 902 of the gearbox I9 is ​​connected to the flywheel energy storage unit 2. The wind energy capture unit 1 of this structure adopts a vertical shaft wind turbine. The transmission ratio of the gearbox I9 is ​​1:15, i.e., a fixed speed ratio. Its function is to convert the low-speed rotation of the wind turbine into high-speed rotation so that it can store wind energy and drive the thermal energy conversion unit even in low wind speed environments. It can also set a maximum allowable speed to limit the speed of the wind turbine in high wind speed environments and prevent the flywheel speed from exceeding its rated speed range.

[0087] During assembly, the low-speed input shaft 901 and the high-speed output shaft 902 are connected to the input shaft 1001 of the rotating shaft 7 and the flywheel 10, respectively, via coupling 13. Coupling 13 is a flexible coupling, the function of which is to reduce vibration and impact during transmission while transmitting mechanical energy, and to maintain stable transmission of speed and torque.

[0088] In the aforementioned wind energy capture unit 1, the blade 5 is the most important energy capture unit. When wind acts on the blade 5 of the wind turbine at a certain speed, it generates a rotational torque, converting the kinetic energy of the incoming wind into rotational mechanical energy. The size and number of blades 5 are matched according to the local wind energy conditions and the required level of mechanical energy (speed / torque). In specific manufacturing, the blade 5 is arc-shaped, and its inner center is connected to the hub 6 through a connecting rod. The hub 6 is used to fix the blade 5 and make the blade 5 drive the rotating shaft 7 to rotate synchronously. The tower 8 is the supporting structure of the wind turbine, which is used to fix the wind turbine to the top of the cabinet 4. Standardized connectors and flanges are used to achieve rapid installation.

[0089] In specific embodiments of the present invention, such as Figure 5 As shown, the flywheel energy storage unit 2 includes a vacuum chamber 14 and a flywheel 10. The flywheel 10 is disposed inside the vacuum chamber 14. The input shaft 1001 of the flywheel 10 passes through the upper wall of the vacuum chamber 14 and is connected to the high-speed output shaft 902 of the transmission gearbox I 9. The output shaft 1002 of the flywheel 10 passes through the lower wall of the vacuum chamber 14 and is connected to the transmission gearbox II 12. The input shaft 1001 and output shaft 1002 of the flywheel 10 are respectively connected to the upper and lower walls of the vacuum chamber 14 through bearings 11, which support the flywheel 10 and ensure its stable rotation. The bearings 11 are air bearings to reduce friction loss and ensure that the flywheel can rotate stably at high speed for a long time. This flywheel energy storage unit 2 is a physical energy storage technology that stores energy in the form of kinetic energy through a high-speed rotating flywheel.

[0090] During assembly, the output shaft 1002 of the flywheel 10 is connected to the high-speed input shaft 1201 of the transmission gearbox II 12 via coupling 13. The low-speed output shaft 1202 of the transmission gearbox II 12 is connected to the drive shaft 1501 of the compressor 15 via coupling 13. Coupling 13 is also a flexible coupling. The transmission gearbox II is used to adjust the speed of the flywheel output shaft, converting the high-speed rotation of the flywheel into a suitable rotational speed to match the speed requirements of the compressor in the heat energy conversion unit, thus preventing over-compression or under-compression of the compressor.

[0091] In its specific manufacturing process, the vacuum chamber 14 is a cylindrical metal container with a diameter of 45cm and a height of 15cm. It is internally vacuumed, and the flywheel and bearings are located inside the vacuum chamber. Its function is to reduce wind resistance loss and ensure the safe operation of the flywheel. The flywheel 10 has a diameter of 40cm and is made of lightweight, high-strength materials such as carbon fiber and aluminum alloy. Its mass is adjusted by its thickness. The advantages of the flywheel are high rotational speed, light weight, low rotational inertia loss, and high energy storage efficiency.

[0092] During operation, the rotating shaft of flywheel 10 directly drives the compressor's drive shaft 1501 via the transmission gearbox II12. Its functions include: 1) providing the high torque required for compressor startup; and 2) maintaining stable compressor speed during wind speed fluctuations. The advantages of this drive scheme are: First, compared to the conventional scheme of driving the compressor via "wind / photovoltaic power generation—electrical energy—motor—mechanical energy," it reduces two energy conversion stages (wind / solar energy to electrical energy, electrical energy to mechanical energy), thereby eliminating the high energy loss rate and safety risks associated with these conversion stages. Second, the entire system operates without electricity, using only mechanical means, making it more weather-resistant and reliable in harsh low-temperature environments.

[0093] The function of the aforementioned flywheel energy storage unit is as follows: After the wind energy capture unit (wind turbine) captures external wind energy, it first drives the flywheel from a stationary state to accelerate to rotation, converting wind energy into the flywheel's kinetic energy, which is stored in the moment of inertia. The greater the moment of inertia, the more kinetic energy is stored. Its beneficial effects are: natural wind speeds are characterized by fluctuations and intermittency. If the wind energy capture unit is directly connected to the heat energy conversion unit, changes in wind speed will directly affect the wind turbine's output power and rotational speed, causing the heat pump unit's operating state to fluctuate with wind speed, affecting operational stability and lifespan. By adding a flywheel energy storage unit between the wind energy capture unit and the heat energy conversion unit, the flywheel accelerates energy storage when wind speed is high; when wind speed is low or there is no wind, the flywheel releases kinetic energy, thus acting as a power buffer to balance the intermittency and fluctuation of wind energy. Moreover, the flywheel has a fast response speed (millisecond level), capable of instantly absorbing or releasing power, smoothly responding to sudden changes in wind speed, thereby improving the stability and endurance of the heat energy conversion unit.

[0094] From the perspective of energy capture and conversion, the wind energy capture unit captures wind energy and converts it into low-grade mechanical energy, which is then upgraded to high-grade mechanical energy through a speed-up transmission mechanism (gearbox I). The flywheel energy storage unit uses the rotational inertia of the flywheel to store high-grade mechanical energy for a short period, avoiding excessive fluctuations in mechanical energy caused by dynamic changes in wind speed, and improving the continuity and stability of mechanical energy output. The thermal energy conversion unit uses mechanical energy to drive a heat pump, collecting low-grade geothermal energy, solar energy, and other renewable thermal energy, and converting it into high-grade thermal energy, actively delivering heat to areas of roadbed frost heave to raise their temperature. The key technical point of this invention is the matching of the rotational speeds of the wind turbine, flywheel, and compressor. The wind turbine speed changes with the wind speed, while the flywheel speed varies within a rated range to store / release energy. The compressor also needs to operate within a specific speed range to ensure heating efficiency and system safety.

[0095] The beneficial effects of the aforementioned heat pump system are as follows: By introducing a flywheel energy storage unit, when wind speed is sufficient, a portion of the mechanical energy is used to drive the heat conversion unit, and the excess mechanical energy drives the flywheel to rotate at high speed to store energy, thus converting it into "high-speed rotational energy storage" for short-term kinetic energy storage. When wind speed is insufficient, the high-speed rotating flywheel converts inertial kinetic energy into mechanical energy, supplementing the rotational speed and torque of the heat conversion unit's drive shaft, acting like a "fast-response regulator" to achieve smooth energy conversion and ensure precise matching between the shaft speed and the compressor. The entire system is electricity-free, green, zero-carbon, and operates completely off-grid, making it suitable for scattered, isolated locations along transportation routes.

[0096] The working process of the heat pump system in this invention is as follows:

[0097] First, the wind turbine converts wind energy into low-speed rotational energy. This low-speed mechanical energy is then converted into high-speed rotating shaft work via a gearbox I, and the flywheel smooths out and stores the energy fluctuations. Next, the high-speed rotating shaft work drives the compressor, which on the one hand allows the heat transfer fluid in the evaporator to extract heat from the low-temperature ground temperature, and on the other hand combines the compressor shaft work with the low-grade heat energy contained in the gaseous heat transfer fluid to convert it into high-grade heat energy. Finally, the high-grade heat energy is transported to the roadbed frost heave layer through the condenser to meet the requirements for roadbed frost heave prevention and control.

[0098] This invention also provides a design method for the above-mentioned heat pump system, such as... Figure 10 As shown, the design of the above heat pump system includes the following steps:

[0099] Step 1: Based on the roadbed heat load, consult the compressor manufacturer's selection manual to determine the compressor model;

[0100] The compressor's heating capacity should be equal to the roadbed's heat load. The compressor's parameters, including its rated speed (W), should be determined using the manual. c(r / min), moment of inertia J c (kg·m²), rated shaft power P c (W), Rated Torque T c (N·m); The starting torque T0 of the compressor is generally equal to the rated torque T. c 2 times.

[0101] Step 2: Match the flywheel according to the compressor drive requirements. Determine the flywheel parameters, including the flywheel's moment of inertia J. f Speed ​​range w f Geometric dimensions (radius R and thickness D of the flywheel) and mass m of the flywheel f .

[0102] (21) Calculate the energy E that the flywheel needs to store. f The calculation method is as follows:

[0103] (1)

[0104] In the formula, E f The energy required to store by the flywheel, J; J c η is the compressor's moment of inertia, kg·m²; η1 is the flywheel's transmission efficiency; w c P is the compressor's rated speed, in r / min; c t is the rated shaft power of the compressor, in W; t is the duration for which the flywheel keeps the compressor running without airflow, in s;

[0105] (22) Based on the energy E that the flywheel needs to store f Choose the flywheel material and determine the design speed range (w). f =[w min w max Calculate the mass m of the flywheel. f The calculation method is as follows:

[0106] (2)

[0107] In the formula, ω max For the maximum design speed w max The corresponding maximum angular velocity, rad / s; ω min For the minimum design speed w min The corresponding minimum angular velocity, rad / s; R is the radius of the flywheel, taken as 0.2m; m f The mass of the flywheel is expressed in kg.

[0108] Based on the calculated flywheel mass m f By combining the known flywheel material (density) and flywheel radius, the flywheel thickness D and the flywheel's moment of inertia can be calculated. Jf This calculation method is well-known and will not be elaborated upon here.

[0109] (23) Verify the maximum torque T of the flywheel f Does it meet the starting torque T0 required by the compressor?

[0110] (3)

[0111] In the formula, α is the maximum allowable angular deceleration of the flywheel, rad / s²; the set value is obtained according to the dynamic response of the system.

[0112] Such as T f If T ≥ T0, then continue with step 3; if T f If <T0, then the design speed range [w] should be redefined. min w max ], until the flywheel's maximum torque T f The starting torque T0 required by the compressor is greater than or equal to the starting torque required by the compressor.

[0113] Step 3: Calculation and selection of the transmission gearbox II between the compressor and the flywheel. The optimal operating speeds of the compressor and flywheel are different, requiring the matching of the transmission gearbox II. The calculation method for the transmission ratio i of the transmission gearbox II is as follows:

[0114] (4)

[0115] Generally, the flywheel is designed to rotate at a speed of w. f Higher than the compressor's rated speed w c Therefore, a second gearbox is needed to reduce the speed. After the speed is reduced, the output torque increases accordingly and is greater than T. f At this point, it is not necessary to verify the flywheel torque performance. Based on the calculated transmission ratio i, select the appropriate gearbox model. Generally, when i < 5, select parallel shaft gears; when i ≥ 5, select planetary gears.

[0116] Step 4: Based on the flywheel design results, calculate and select the wind energy harvesting unit, including the required input power P. w and torque T w .

[0117] (41) Calculate the power input P required by the flywheel. w Based on the model of gearbox II in step 3, determine the transmission efficiency η2 of gearbox II. η3 is the transmission efficiency of gearbox I (constant speed ratio). The calculation method is as follows:

[0118] (5)

[0119] η1, η2, and η3 were obtained by consulting the mechanical design handbook.

[0120] (42) Calculate the required input rotational speed w of the wind energy capture unit. w and torque T w The calculation method is as follows:

[0121] (6)

[0122] (7)

[0123] (43) Perform torque matching calculations to ensure that the flywheel can be driven. If T w ≥i·T f The requirements are met; if T w <i·T f Then, starting from step 2, the design calculations are re-performed to form the first iterative optimization design process.

[0124] Step 5: Calculate and select the wind turbine in the wind energy capture unit based on the wind energy conditions at the application site.

[0125] (51) Investigate and determine the average winter wind speed v (m / s) of the location, and calculate the radius r of the wind turbine. The calculation method is as follows:

[0126] (8)

[0127] In the formula, C p ρ is the wind energy utilization coefficient; ρ is the air density, kg / m³ 3 In this invention, the wind energy capture unit is a vertical shaft wind turbine, C p The value is 0.3.

[0128] The radius of the wind turbine refers to the radius of the largest circle in the blade trajectory during the wind turbine's rotation.

[0129] (52) Perform speed matching calculation. Under the conditions of local wind speed and rotor radius, the actual rotor speed w0 is:

[0130] (9)

[0131] In the formula, λ is the tip speed ratio of the wind turbine. In this invention, a vertical shaft wind turbine is selected as the wind energy capture unit, and λ=7.

[0132] If w0 ≥ w w This meets the design requirements; if w0 < w w Starting from step 2, the design calculations are re-performed, forming the second iterative optimization design process.

[0133] In summary, the advancements achieved by this invention compared to existing technologies are as follows:

[0134] (1) Wind energy thermal utilization technology. An innovative idea of ​​using wind energy to directly drive a compression heat pump unit (thermal energy conversion unit) is proposed. Compared with electric heat pump, the direct-drive wind turbine heat pump system reduces the energy conversion loss between wind energy and electric energy, reduces the system cost, and improves the overall conversion efficiency.

[0135] (2) Using shallow geothermal energy in the foundation as the main heat source and wind energy as the driving force for heat conversion, it makes full use of the resource advantages of high wind speed in winter and stable geothermal energy reserves, which is green and environmentally friendly.

[0136] (3) Given the real-time correlation between wind energy fluctuation characteristics and heat pump operating status, a flywheel energy storage unit is innovatively introduced to optimize "wind energy-mechanical energy" into "wind energy-mechanical energy-kinetic energy". On the one hand, it smooths and filters the fluctuation of wind energy, and on the other hand, it stores the mechanical energy overflowing when the wind speed is high, so that it can be output when the wind speed is low, enabling the compressor to continuously obtain sufficient shaft work and play a role in peak shaving and valley filling. This overcomes the fluctuation and instability of wind energy itself and improves the stability and continuity of heat pump heating performance.

[0137] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention 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 the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions, characterized in that: The heat pump system includes a wind energy capture unit, a flywheel energy storage unit, and a thermal energy conversion unit. The output of the wind energy capture unit is connected to the input of the flywheel energy storage unit, and the output of the flywheel energy storage unit is connected to the input of the thermal energy conversion unit. The wind energy capture unit captures wind energy, converts it into mechanical energy, and stores it in the flywheel energy storage unit. The flywheel energy storage unit drives the thermal energy conversion unit. The thermal energy conversion unit collects low-grade renewable thermal energy and converts it into high-grade thermal energy to deliver heat to the frost heave-affected areas of the roadbed.

2. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 1, characterized in that: The heat energy conversion unit includes a compressor, a condenser, a liquid receiver, a dryer filter, a throttle valve, and an evaporator. The exhaust port of the compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the liquid receiver, the outlet of the liquid receiver is connected to the inlet of the dryer filter, the outlet of the dryer filter is connected to the inlet of the throttle valve, the outlet of the throttle valve is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the return port of the compressor, thereby forming a closed loop internally filled with heat transfer fluid. The storage tank is used to store the liquid heat transfer fluid and regulate its flow rate to the throttle. The evaporator is located in the foundation at a distance of 400cm from the toe of the roadbed slope to prevent the heat absorption and cooling zone of the foundation from spreading to the roadbed. On the cross section of the roadbed, the condenser is located at 1 / 3 of the maximum vertical freezing depth of the roadbed frost heave layer.

3. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 2, characterized in that: The compressor has a rated speed range of 600-1000 r / min and a rated torque range of 50-100 N·m; the dryer filter is a molecular sieve filter, and the throttling device is a capillary tube; the evaporator is made of copper tube with an outer diameter of 8 mm, a wall thickness of 0.6 mm, and an inner diameter of 6.8 mm, and the condenser is made of copper tube with an outer diameter of 6 mm, a wall thickness of 0.6 mm, and an inner diameter of 4.8 mm. Both the evaporator and the condenser are spiral columns; both the evaporator and the condenser are equipped with buried sleeves.

4. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 2, characterized in that: The heat transfer medium is R134a, and the evaporation temperature range of R134a is -10 to -25°C, and the condensation temperature range is 40 to 60°C.

5. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 2, characterized in that: The compressor, liquid storage tank, dryer filter, and throttling device of the flywheel energy storage unit and the thermal energy conversion unit are all installed in the cabinet. The wind energy capture unit is installed on the top of the outside of the cabinet. The cabinet is installed on the foundation on the side of the roadbed. Multiple heat pump systems are arranged at intervals along the longitudinal length of the roadbed according to the frost heave disease, and the distance between two adjacent heat pump systems is 2.0m-4.0m.

6. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 5, characterized in that: The cabinet has an upper and lower support plate inside, and guide rails that mate with the upper and lower support plates are provided on the inner walls of both sides of the cabinet. The flywheel energy storage unit is located on the upper support plate, and the compressor, liquid storage tank, dryer filter and throttle are all located on the lower support plate. The bottom of both sides of the cabinet has pipe openings for connecting pipelines to the condenser and evaporator, and the outside of the pipe openings is equipped with dust covers.

7. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 5, characterized in that: The wind energy capture unit includes a wind turbine and its lower shaft. The wind turbine includes a hub and multiple blades, which are radially distributed around the hub. The shaft is located at the lower end of the hub and is mounted on the top of the cabinet via a tower. The lower end of the shaft passes through the tower and the top wall of the cabinet and is connected to the low-speed input shaft of the gearbox I. The high-speed output shaft of the gearbox I is connected to the flywheel energy storage unit.

8. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 7, characterized in that: The flywheel energy storage unit includes a vacuum chamber and a flywheel. The flywheel is disposed in the vacuum chamber. The input shaft of the flywheel passes through the upper wall of the vacuum chamber and is connected to the high-speed output shaft of the gearbox I. The output shaft of the flywheel passes through the lower wall of the vacuum chamber and is connected to the gearbox II. The input shaft and output shaft of the flywheel are respectively connected to the upper and lower walls of the vacuum chamber through bearings.

9. A heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions according to claim 8, characterized in that: The vacuum chamber is a cylindrical tank with a diameter of 45cm and a height of 15cm; the flywheel has a diameter of 40cm and is made of lightweight, high-strength material; the bearing is an air bearing.

10. A design method for a heat pump system for preventing and controlling frost heave disease in roadbeds in cold regions, characterized in that, Designing the heat pump system as described in claim 8 includes the following steps: Step 1: Determine the compressor model based on the roadbed heat load; Step 2: Design the flywheel according to the compressor's drive requirements; (21) Calculate the energy E that the flywheel needs to store. f The calculation method is as follows: （1） In the formula, E f The energy required to store by the flywheel, J; J c η is the compressor's moment of inertia, kg·m²; η1 is the flywheel's transmission efficiency; w c P is the compressor's rated speed, in r / min; c t is the rated shaft power of the compressor, in W; t is the duration for which the flywheel keeps the compressor running without airflow, in s; (22) Based on the energy E that the flywheel needs to store f Choose the flywheel material and design the rotational speed range (w). f =[w min w max Calculate the mass m of the flywheel. f The calculation method is as follows: （2） In the formula, ω max For the maximum design speed w max The corresponding maximum angular velocity, rad / s; ω min For the minimum design speed w min The corresponding minimum angular velocity, rad / s; R is the radius of the flywheel; m f The mass of the flywheel is expressed in kg. (23) Verify the maximum torque T of the flywheel f Does it meet the starting torque T0 required by the compressor? The starting torque T0 of the compressor is its rated torque T. c 2 times; （3） In the formula, α is the maximum allowable angular deceleration of the flywheel, in rad / s²; Such as T f If T ≥ T0, then continue with step 3; if T f If <T0, then the design speed range [w] should be redefined. min w max ], until the flywheel's maximum torque T f The starting torque T0 required by the compressor is greater than or equal to the starting torque required by the compressor. Step 3: Calculation and selection of the transmission gearbox II between the compressor and the flywheel; The method for calculating the transmission ratio i of gearbox II is as follows: （4） When i < 5, choose a parallel shaft gear; when i ≥ 5, choose a planetary gear. Step 4: Based on the flywheel design results, calculate and select the wind energy harvesting unit; (41) Calculate the power input P required by the flywheel. w Based on the model of gearbox II in step 3, determine the transmission efficiency η2 of gearbox II, and η3 is the transmission efficiency of gearbox I. The calculation method is as follows: （5） (42) Calculate the required input rotational speed w of the wind energy capture unit. w and torque T w The calculation method is as follows: （6） （7） (43) Perform torque matching calculations to ensure that the flywheel can be driven; If T w ≥i·T f The requirements are met; if T w <i·T f Then, the design calculation is repeated from step 2, forming the first iterative optimization design process; Step 5: Calculate and select the wind turbine in the wind energy capture unit based on the wind energy conditions at the application site. (51) Investigate and determine the average winter wind speed v of the location, and calculate the radius r of the wind turbine. The calculation method is as follows: （8） In the formula, C p ρ is the wind energy utilization coefficient; ρ is the air density, kg / m³ 3 v represents the average winter wind speed at the application site location, in m / s. (52) Perform speed matching check; Given the wind speed and rotor radius at the application site, the actual rotor speed w0 is: （9） In the formula, λ is the tip speed ratio of the wind turbine blades; If w0 ≥ w w This meets the design requirements; if w0 < w w Starting from step 2, the design calculations are re-performed, forming the second iterative optimization design process.

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