Railway subgrade frost heave disease prevention and control system and method adapted to severe cold climates

Abstract

The present invention discloses a system and method for preventing and controlling frost heave damage in railway subgrades adapted to severe cold climates. This system belongs to the field of seasonal frozen soil engineering technology. The prevention and control system includes several ground-source heat pump devices consisting of heating units, heating pipes, heat collecting pipes, and a detection assembly. Several heating units are arranged at the foot of the subgrade slope along the length of the railway. The heating pipes are laid in the frost heave development layer of the subgrade, and the heat collecting pipes are installed in the stable layers of the foundation on both sides of the subgrade. A heat carrier circulates through the pipeline consisting of the heating pipes, heating units, and heat collecting pipes. Temperature sensors, pressure sensors, and displacement sensors are used to monitor the subgrade freezing temperature, heat carrier temperature, compressor intake and exhaust pressures, and track deformation, respectively. A control assembly receives signals from the detection assembly and controls the operating mode of the heating units. The present invention ensures rapid compressor superheat establishment during startup in severe cold environments and rationally controls the compressor exhaust temperature range and operating mode during normal operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of seasonal frozen soil engineering, and in particular relates to a railway subgrade frost heave disease prevention and control system and method adapted to severe cold climates. Background Art

[0002] Unlike the thaw settlement challenges faced by railway operations in permafrost areas, the primary challenge facing railway operations in deep-season permafrost areas is winter frost heave damage in some sections of the roadbed. This problem stems from the formation of discontinuously distributed moisture-rich zones within the roadbed filler due to capillary recharge of local shallow groundwater and precipitation infiltration at individual damaged locations. The freezing and expansion of this moisture causes uneven frost heave deformation on the roadbed top surface, which in turn leads to irregular track geometry and compromises driving safety. Conventional frost heave prevention and control measures primarily rely on human and physical defenses, including track frost heave pads, in-situ grouting of the roadbed, filler replacement, drainage, and insulation structures. However, these measures are limited in effectiveness and timeliness for stubborn and sudden frost heaves, and lack the ability to quickly eliminate frost heave deformations once they occur. This makes it difficult to address frost damage in critical areas such as transition sections, junctions, and curves. To address this, the railway industry has begun introducing artificial heating technology, which actively injects heat into the frost heave layers of the roadbed and raises the temperature to eradicate frost heave. For example, patent application number CN201820317204.1 discloses a ground-source heat pump device for preventing frost heave in roadbeds in seasonally frozen areas. This system uses geothermal energy as a heat source and a heat pump as a means of heat energy conversion and transmission. Patent application number CN202211115741.5 discloses a frost-heave-resistant roadbed system and a roadbed heating method. This system is a ground-source heat pump system that provides intermittent heating in stages based on the roadbed's heat load.

[0003] In the above-disclosed patent documents, the heat pump is the key heat energy carrier, and the compressor is the core driving component of the heat pump. Its function is to provide power for the phase change cycle of the heat carrier and the heat conversion and transmission. In recent years, the heat pump anti-frost heave system has been applied to national trunk railways such as the Qinghai-Tibet Railway, Lanzhou-Xinjiang Railway, and Shenyang-Baidu High-speed Railway. Railway subgrade frost heave disease often occurs in cold climate zones with low ambient temperatures and high frequency of cold waves. Instantaneous extreme low temperatures in winter can reach about -40°C, and the freezing period lasts from November each year to April of the following year. The main problems found in the application of heat pumps are as follows:

[0004] First, from the perspective of heat pump startup, due to the low temperatures in winter in severely cold climates, the heat transfer agent return temperature at the compressor inlet is too low during the initial startup phase, making it difficult to quickly establish the required superheat for the compressor, and the time required from startup to normal operation is excessively long. Second, from the perspective of heat pump operation, due to the low quality and low density of geothermal energy in severely cold climates, the geothermal energy collection efficiency gradually decreases after the heat pump enters normal operation, causing a decrease in the vaporization rate of the heat transfer agent in the foundation heat collection pipes on the low-pressure side of the heat pump. This reduces the heat transfer agent return flow rate in the compressor and the heat transfer agent flow rate in the high-pressure side heating components. This leads to adverse consequences such as excessively high compressor exhaust temperature, deterioration of the internal lubricating oil and oil film damage, and insufficient heating capacity, making it difficult to meet the requirements for roadbed frost heave prevention and control. When the heat transfer agent's evaporation pressure approaches atmospheric pressure, negative pressure may even occur within the low-pressure side heat collection components, causing the compressor to run dry, and the compressor failure rate to increase sharply. Third, when preventing and controlling frost heave disease on the roadbed, the operation control of the heat pump is based on the roadbed temperature, with the goal of eliminating the frozen state of the roadbed. Blindly increasing the heating capacity requirement causes heat overflow loss in non-frost heave disease areas, resulting in high energy consumption of the heat pump, an imbalance between the use cost and the equipment installation cost, and poor economy.

[0005] In short, heat pumps in extremely cold climates have widespread limitations such as slow startup speed, short stable operation time, high operating energy consumption, and low long-term life, which restricts the practicality of ground-source heat pump technology in solving the problem of frost heave disease on railway subgrades.

[0006] It can be seen that solving the three problems of low-temperature startup speed, stable operation time and operation control energy efficiency of ground source heat pump systems in severe cold climate environments is the key to improving the timeliness, efficiency, reliability, energy saving and economy of the prevention and control of frost heave diseases of railway subgrades in severe cold regions. Summary of the Invention

[0007] The present invention provides a railway subgrade frost heave disease prevention and control system and method that can adapt to severe cold climates. The system aims to solve the technical problems of the compressor, the core driving component of the existing subgrade source heat pump system, in severe cold climate environments, such as slow start-up speed, short stable operation time, high operating energy consumption, and short long-term life.

[0008] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0009] A railway subgrade frost heave disease prevention and control system adapted to severe cold climates comprises a plurality of ground-source heat pump devices spaced apart along the length of the railway subgrade. The ground-source heat pump devices comprise a heating unit, a heat supply pipe, a heat collection pipe, and a detection assembly. The heat collection pipe is connected to the heat supply pipe via the heating unit. The heating unit is located on the surface of the subgrade at the toe of the subgrade. The heat supply pipe is laid horizontally in the frost heave development layer of the subgrade and perpendicular to the length of the subgrade. The heat collection pipe is located vertically in the lower stabilization layer of the subgrade on both sides of the subgrade.

[0010] The detection component includes a temperature sensor, a pressure sensor and a displacement sensor. Temperature sensors are installed in the roadbed, in the middle of the heat collecting pipe and on the pipeline of the heating unit, which are respectively used to monitor the harmful freezing temperature of the roadbed and the temperature of the heat carrier in the pipeline; the compressor return air port and the compressor exhaust port of the heating unit are both provided with pressure sensors for monitoring the suction and exhaust pressures of the compressor; the displacement sensor is arranged at the waist of the railway track to detect the deformation of the track. The heating unit, temperature sensor, pressure sensor and displacement sensor are all connected to the control component.

[0011] Furthermore, the heating unit includes a cabinet and a heating component, wherein the heating component and the control component are both arranged in the cabinet, the heating component is connected to the heat supply pipe and the heat collection pipe through a pipeline, and the heating component can realize the condensation and liquefaction and evaporation and gasification of the heat carrier, which are respectively used to supply heat to the roadbed and absorb heat from the foundation;

[0012] The heating assembly includes a compressor, a gas-liquid separator I, a liquid storage tank, a throttle and a gas-liquid separator II. The compressor exhaust port is connected to the inlet A of the electromagnetic three-way valve I, the outlet B of the electromagnetic three-way valve I is connected to the inlet of the heating pipe, the outlet of the heating pipe is connected to the inlet A of the gas-liquid separator I, the liquid outlet B of the gas-liquid separator I is connected to the inlet of the liquid storage tank, the outlet of the liquid storage tank is connected to the inlet A of the electromagnetic three-way valve II, the outlet B of the electromagnetic three-way valve II is connected to the inlet of the throttle, the outlet of the throttle is connected to the inlet of the heat collecting pipe, the outlet of the heat collecting pipe is connected to the inlet A of the gas-liquid separator II, the gas outlet C of the gas-liquid separator II is connected to the inlet A of the electromagnetic three-way valve III, the outlet B of the electromagnetic three-way valve III is connected to the inlet of the return pipe, the outlet of the return pipe is connected to the return air port of the compressor, and the return air pipe is coiled on the compressor casing. The above circuit forms a main circulation loop of the heat carrier;

[0013] It also includes a mixing chamber, wherein the gas outlet C of the gas-liquid separator I is connected to one inlet of the mixing chamber via a connecting pipe, and the other inlet of the mixing chamber is connected to the liquid outlet B of the gas-liquid separator II via a connecting pipe. The outlet of the mixing chamber is connected to the pipeline between the gas-liquid separator II and the electromagnetic three-way valve III via a connecting pipe. Each connecting pipe is provided with a one-way valve, forming a first auxiliary branch of the heat carrier;

[0014] The compressor superheat rapid improvement component includes a return air pipe and a bypass pipe, the bypass pipe is provided with a heating jacket on the outside, the inlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve I, and the outlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve III, forming a second auxiliary branch of the heat carrier;

[0015] It also includes a compressor exhaust temperature balancing and regulating component, which includes an electromagnetic flow valve and a capillary tube. The electromagnetic flow valve is arranged on the capillary tube, the inlet of the electromagnetic flow valve is connected to the auxiliary port C of the electromagnetic three-way valve II, the outlet of the electromagnetic flow valve is connected to the inlet of the capillary tube, and the outlet of the capillary tube is connected to the heat carrier injection port of the compressor, forming a third auxiliary branch of the heat carrier.

[0016] Furthermore, the return air pipe is a copper tube with an outer diameter of 10.0 mm, a wall thickness of 1.0 mm, and a length of 2.5 m. The return air pipe is spirally coiled on the outer casing of the compressor; the bypass pipe is a copper tube with an outer diameter of 16.0 mm and a wall thickness of 1.0 mm. The bypass pipe inside the heating jacket is spiral. The rated power of the heating jacket is 50 W, and the heating temperature is 40°C; the capillary tube is a copper tube with an outer diameter of 3.0 mm and a wall thickness of 0.5 mm. The length of the capillary tube is in cm, and the value is 1 / 5 of the rated power of the compressor.

[0017] Furthermore, the control component includes a PLC controller and a control panel, and the temperature sensor, pressure sensor, displacement sensor, throttle, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, heating jacket, and electromagnetic flow valve are all connected to the PLC controller, and the PLC controller, compressor, gas-liquid separator I, and gas-liquid separator II are all connected to the control panel.

[0018] Furthermore, the heat collecting tube includes a tube body and a protective cover at its end. The tube body is composed of an outer sleeve and a base tube from the outside to the inside. The inner cavity of the base tube is filled with heat storage material. The outer surface of the base tube is spirally coiled with a heat carrier circulation tube. Heat-conducting mortar is filled between the base tube and the outer sleeve, and the heat carrier circulation tube is immersed in the heat-conducting mortar. The heat supply tube and the heat collecting tube have the same structure.

[0019] Furthermore, the outer casing is a 201 stainless steel pipe with an outer diameter of 114 mm and a wall thickness of 2 mm, and the thermal conductive mortar is a metal-based thermal conductive mortar with a thermal conductivity of 2.0 to 2.5 W / (m·K). The thermal conductivity of the heating pipe and the heat collecting pipe is higher than that of the roadbed filler, which is 0.5 to 2.0 W / (m·K).

[0020] The heat transfer medium circulation pipe is a copper tube with an outer diameter of 6.0mm and a wall thickness of 0.6mm; the base pipe is a steel mesh skeleton composite PVC pipe with an outer diameter of 75mm; the heat storage material is silt or sand with a moisture content of 20% to 30%;

[0021] The heat carrier is a medium-high temperature heat carrier R134a, which has a boiling point of -26.1°C and a critical temperature of 101.1°C. The charge amount of the heat carrier is in grams, which is 3.5 times the rated power of the compressor.

[0022] The compressor adopts a fully enclosed single-type piston compressor with a rated input power of 100-600W; the gas-liquid separator I selects a gravity sedimentation type separator, and the gas-liquid separator II selects a baffle separation type separator; the liquid storage tank adopts an inverted cone tank body, and the throttle adopts an electronic expansion valve.

[0023] Furthermore, the cabinet includes a cabinet body and a base at the bottom thereof, the front side of the cabinet body is provided with a cabinet door that can be opened and closed, and the interior is divided into three layers by two parallel support plates in the middle, the two support plates are respectively an upper support plate and a lower support plate, and the sides of the upper support plate and the lower support plate are respectively slidably matched with the guide rails on the inner wall of the cabinet body; an upper shield plate and a lower shield plate arranged vertically up and down are provided on the inner side of the cabinet door, the upper shield plate and the lower shield plate are arranged on the outer side of the guide rail, and the upper support plate is provided between the upper shield plate and the lower shield plate; the control component is provided on the upper shield plate, and a left window and a right window are respectively provided on the left and right side walls of the cabinet body;

[0024] The compressor, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, liquid storage tank and mixing chamber are arranged on the upper support plate, and the bypass pipe, electromagnetic flow valve, capillary tube, gas-liquid separator I, throttle and gas-liquid separator II are arranged on the lower support plate; the control component is arranged on the upper shield plate.

[0025] The present invention also provides a method for preventing and controlling railway subgrade frost heave disease that is adaptable to severe cold climates, comprising the following steps:

[0026] 1) Assemble and install the above-mentioned prevention and control system, design the layout parameters of the heating pipes and collector pipes and the heating capacity of the heating units;

[0027] Start the ground-source heat pump device and enter the design parameters on the control panel of the control component; start the compressor and open the main circulation loop at the same time, close the second auxiliary branch of the compressor superheat rapid increase component and the third auxiliary branch of the compressor exhaust temperature equalization adjustment component;

[0028] 2) Regularly collect the measured values ​​of the temperature sensor on the roadbed and the displacement sensor on the track at a fixed interval of 10-30 minutes;

[0029] 3) The PLC controller of the control component calculates the differential frost heave deformation of the track structure, that is, the amplitude of the track's unevenness, and obtains the subgrade freezing depth and the average temperature of the harmful freezing depth range based on linear interpolation of the subgrade temperature sensor;

[0030] 4) When the differential frost heave deformation is less than the specified track height irregularity management limit, it indicates that the track is in the frost heave disease prevention stage. The operation mode control scheme of the ground source heat pump device is as follows:

[0031] Based on the weather forecast and the measured data from step 2), the PLC controller calculates the required heating capacity and obtains the required heat transfer agent flow and the corresponding throttle opening at a fixed interval t of 10-30 minutes;

[0032] The heat transfer medium flow rate is calculated by dividing the heating power of a single heat pump by the phase change latent heat value of the heat transfer medium. The throttle opening is calculated by the ratio of the heat transfer medium flow rate to the maximum allowable flow rate.

[0033] 5) When the differential frost heave deformation exceeds the specified track height irregularity management limit, it indicates that the frost heave disease has entered the post-disaster rapid remediation stage; the operating mode control scheme of the ground source heat pump device is as follows:

[0034] The throttle opening is opened to 70% until the differential frost heave deformation of the track is reduced to within the management limit, and then the operation mode of step 4 is restored.

[0035] Furthermore, in step 4), the operating mode of the ground source heat pump device is adjusted by the operating state of the compressor, and the adjustment logic is as follows:

[0036] 1) Sense and display the temperature and pressure sensors located in the heating unit at a fixed interval of 10 minutes;

[0037] 2) The PLC controls and calculates the compressor's evaluation indicators, including compression ratio, suction superheat, and discharge superheat;

[0038] 3) Based on the compressor evaluation index, execute the control commands for the compressor superheat rapid increase component and the compressor exhaust temperature balance adjustment component. The specific plan is as follows:

[0039] ①When the suction superheat is displayed below 5℃, the PLC controls the opening of the compressor superheat rapid increase component;

[0040] ② When the displayed compression ratio is greater than 8, the PLC controls the compressor exhaust temperature equalization adjustment component to release 1 / 200 of the total heat carrier charge per minute to increase the heat transfer rate;

[0041] ③ When the exhaust gas superheat is displayed to be greater than 20℃, the PLC controls the compressor exhaust gas temperature equalization adjustment component to release 1 / 100 of the total heat carrier charge per minute to perform liquid spray cooling;

[0042] The operations of the above steps ①, ②, and ③ are all performed at fixed intervals of 10 minutes, and the opening and closing of the compressor superheat rapid improvement component and the compressor exhaust temperature equalization adjustment component are adjusted according to the corresponding compressor evaluation indicators.

[0043] Furthermore, in step 1), the longitudinal spacing between the heating pipes of adjacent roadbeds is 2R, and the heat affected radius of the heating pipe is calculated as follows:

[0044] (1)

[0045] Where, T 0 is the outer wall temperature of the heating pipe, which is equal to the set value of the compressor exhaust temperature, °C; T f is the target temperature of the roadbed filler, which is generally taken as the freezing temperature of the filler, °C; Ts is the lowest daily average temperature of the ordinary roadbed during the freezing period with a harmful freezing depth, °C; K s is the correction coefficient of the roadbed filler, which is taken as the compaction coefficient of the roadbed, that is, when the roadbed is poorly compacted, the heat affected radius decreases accordingly; a is the filler thermal diffusivity, m 2 / h; τ is time, h; H 1 is the harmful freezing depth of the roadbed, m;

[0046] The railway track gauge is 1.435m. The heating pipes on both sides are laid directly below the rails on both sides of the center of the railway line. The length of the heating pipes is calculated as follows:

[0047] (2)

[0048] Where, k is the width-to-height ratio of the roadbed slope; b is the shoulder width, m; B The width of the trackbed of a single-track railway or the width of the trackbed of the upline or downline of a double-track railway, in m;

[0049] The heating capacity of the heating unit is calculated as follows:

[0050] (3)

[0051] Where, λ 1 is the surface convection heat transfer coefficient, W / (m 2 ℃); h is the roadbed height, m; T a is the daily average temperature; Δ H is the growth rate of freezing depth of ordinary roadbed, m / s; ρ is the density of the roadbed filler, kg / m 3 ; c is the specific heat capacity of the roadbed filler, J / (kg·℃);

[0052] The height of the heat collecting tube is calculated as follows:

[0053] (4)

[0054] Where H2 is the buried depth of the top of the heat transfer medium circulation pipeline, which is the maximum freezing depth of the natural surface, m; d is the equivalent heat absorption diameter of the stainless steel outer casing for geothermal energy, m; λ 2 is the heat transfer coefficient of the contact interface between the stainless steel outer casing and the foundation soil, W / (m 2 ℃); T e is the average temperature of the heat transfer medium circulation pipeline of the ground-based heat collecting tube, ℃; T g It is the average ground temperature below the maximum freezing depth of the foundation.

[0055] Compared with the prior art, the present invention has the following technical advances:

[0056] The present invention arranges several heating units at intervals along the length of the railway at the foot of the roadbed slope, lays heating pipes horizontally in the frost heave layer of the roadbed, and arranges heat collecting pipes in the lower stable layer of the foundation on both sides of the roadbed. The heating pipes are connected to the heat collecting pipes through the heating units. Temperature sensors, pressure sensors, and displacement sensors are used to monitor the harmful freezing temperature of the roadbed and the temperature of the heat carrier in the pipeline, monitor the suction and exhaust pressures of the compressor, and detect the deformation of the track. The mixing chamber of the heating component, the compressor superheat rapid increase component, and the compressor exhaust temperature equalization adjustment component respectively constitute three auxiliary branches that can protect and improve the heating performance of the main circulation loop. The use of this invention can ensure the rapid establishment of compressor superheat during the startup phase of the ground-source heat pump device in severe cold environments, and reasonably control the compressor exhaust temperature range and operating mode during normal operation, thereby achieving rapid startup and long-term stable operation of the compressor in severe cold climates, reducing operating energy consumption, and increasing service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0058] In the attached figure:

[0059] Figure 1 A schematic diagram of the arrangement of a railway subgrade frost heave disease prevention and control system adapted to severe cold climates, provided by an embodiment of the present invention, inside and outside the railway subgrade;

[0060] Figure 2 Schematic diagram of the structure of a ground source heat pump device in an embodiment of the present invention;

[0061] Figure 3 for Figure 1Schematic diagram of the layout of the ground source heat pump device relative to the railway subgrade;

[0062] Figure 4 A schematic structural diagram of a cabinet in an embodiment of the present invention;

[0063] Figure 5 is an outline diagram of a compressor according to an embodiment of the present invention;

[0064] Figure 6 Schematic diagram of the structure of the electromagnetic three-way valve 1 in an embodiment of the present invention;

[0065] Figure 7 Schematic diagram of the structure of the gas-liquid separator 1 in an embodiment of the present invention;

[0066] Figure 8 Schematic diagram of the structure of the gas-liquid separator II in an embodiment of the present invention;

[0067] Figure 9 Schematic diagram of the installation of the bypass pipe in an embodiment of the present invention;

[0068] Figure 10 This is an external view of the tube body in an embodiment of the present invention;

[0069] Figure 11 for Figure 10 Schematic diagram of the internal structure of the middle tube;

[0070] Figure 12 for Figure 10 Schematic diagram of the cross-section structure of the middle tube body;

[0071] Figure 13 This is a working principle diagram of a ground source heat pump device in an embodiment of the present invention;

[0072] Figure 14 This is a structural layout diagram of the upper support plate of the cabinet in an embodiment of the present invention;

[0073] Figure 15 This is a structural layout diagram of the lower support plate of the cabinet in an embodiment of the present invention;

[0074] Figure 16 Schematic diagram of the arrangement of the heating unit in the cabinet according to an embodiment of the present invention;

[0075] In the picture:

[0076] 1-Heating unit, 2-Heating pipe, 3-Collector pipe, 4-Roadbed, 5-Foundation, 6-Cabinet, 601-Base, 602-Cabinet body, 603-Upper support plate, 604-Lower support plate, 605-Upper shield, 606-Lower shield, 607-Left window, 608-Right window, 7-Compressor, 701-Compressor return air port, 702-Compressor exhaust port, 703-Compressor heat carrier injection port , 8- electromagnetic three-way valve I, 801- inlet A of electromagnetic three-way valve I, 802- outlet B of electromagnetic three-way valve I, 803- auxiliary port C of electromagnetic three-way valve I, 9- gas-liquid separator I, 901- inlet A of gas-liquid separator I, 902- liquid outlet B of gas-liquid separator I, 903- gas outlet C of gas-liquid separator I, 10- liquid storage tank, 11- electromagnetic three-way valve II, 1102- electromagnetic three-way valve Outlet B of valve II, 1103-auxiliary port C of electromagnetic three-way valve II, 12-throttle, 13-gas-liquid separator II, 1301-inlet A of gas-liquid separator II, 1302-liquid outlet B of gas-liquid separator II, 1303-gas outlet C of gas-liquid separator II, 14-electromagnetic three-way valve III, 1401-inlet A of electromagnetic three-way valve III, 1403-auxiliary port C of electromagnetic three-way valve III, 15-return air pipe, 16-connecting pipe, 17-mixing chamber, 18-check valve, 19-bypass pipe, 20-electric heating jacket, 21-electromagnetic flow valve, 22-capillary tube; 26-track, 27-PLC controller, 28-control panel, 29-tube body, 30-protective cover, 31-outer casing, 32-thermal mortar, 33-heat carrier circulation pipe, 34-base pipe, 35-heat storage material. DETAILED DESCRIPTION

[0077] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0078] like Figure 1 、 Figure 2 and Figure 3As shown, a railway subgrade frost heave disease prevention and control system adapted to severe cold climates, the prevention and control system comprises a plurality of ground source heat pump devices spaced apart along the length direction of the railway subgrade 4, the ground source heat pump device comprises a heating unit 1, a heating pipe 2, a heat collecting pipe 3 and a detection component, the heat collecting pipe 3 is connected to the heating pipe 2 through the heating unit 1; the heating unit 1 is located on the surface of the foundation 5 at the foot of the subgrade 4, the heating pipe 2 is horizontally laid in the frost heave development layer of the subgrade 4 and perpendicular to the length direction of the subgrade 4, and the heat collecting pipe 3 is vertically located in the lower stabilization layer of the foundation 5 on both sides of the subgrade 4; The detection component includes a temperature sensor, a pressure sensor and a displacement sensor. Temperature sensors are provided in the roadbed 4, in the middle of the heat collecting pipe 3 and on the pipeline of the heating unit 1, which are respectively used to monitor the harmful freezing temperature of the roadbed and the temperature of the heat carrier in the pipeline; the compressor return air port and the compressor exhaust port of the heating unit 1 are both provided with pressure sensors for monitoring the suction and exhaust pressures of the compressor; the displacement sensor is arranged at the waist of the railway track 26 to detect the deformation of the track 26. The heating unit 1, temperature sensor, pressure sensor and displacement sensor are all connected to the control component.

[0079] During the specific design, five temperature sensors are designed: the first temperature sensor is arranged in the middle position of the heat collecting pipe 3 to monitor the evaporation temperature; the second temperature sensor is arranged on the return air pipe 15 close to the compressor return air port 701 to monitor the return air temperature of the heat carrier entering the compressor; the third temperature sensor is arranged on the pipeline close to the compressor exhaust port 702 to monitor the exhaust temperature of the heat carrier discharged after the compressor works; the fourth temperature sensor is arranged on the top surface of the roadbed 4; the fifth temperature sensor is arranged at the harmful freezing depth of the roadbed.

[0080] There are two pressure sensors: the first is located in the return air pipe 15 of the compressor return air port 701 to monitor the compressor suction pressure, and the second is located in the pipe of the compressor exhaust port 702 to monitor the compressor exhaust pressure.

[0081] Two displacement sensors are designed: the first displacement sensor is arranged at the rail waist position of the upper track 26 at the mileage where the roadbed heating pipe is located, and the second displacement sensor is arranged at the rail waist position of the upper track structure at the middle mileage of the adjacent heating pipe on the same side track, respectively monitoring the absolute frost heave and differential frost heave of the track.

[0082] In a specific embodiment of the present invention, Figure 6-8, 13, and 16, the heating unit 1 includes a cabinet 6 and a heating component, the heating component and the control component are both arranged in the cabinet 6, the heating component is connected to the heating pipe 2 and the heat collecting pipe 3 through a pipeline, the heating component can realize the condensation and liquefaction and evaporation and gasification of the heat carrier, which are respectively used to supply heat to the roadbed 4 and absorb heat from the foundation 5; the heating component includes a compressor 7, a gas-liquid separator I9, a liquid storage tank 10, a throttle 12, a gas-liquid separator II13, a mixing chamber 17, a compressor superheat rapid improvement component and a compressor exhaust temperature balancing adjustment component, the compressor exhaust port 702 is connected to the inlet A801 ​​of the electromagnetic three-way valve I8, the outlet B802 of the electromagnetic three-way valve I is connected to the inlet of the heating pipe 2, and the outlet of the heating pipe 2 is connected to the gas-liquid separator I 9 is connected, the liquid outlet B902 of the gas-liquid separator I9 is ​​connected to the inlet of the liquid storage tank 10, the outlet of the liquid storage tank 10 is connected to the inlet A of the electromagnetic three-way valve II11, the outlet B1102 of the electromagnetic three-way valve II11 is connected to the inlet of the throttle 12, the outlet of the throttle 12 is connected to the inlet of the heat collecting pipe 3, the outlet of the heat collecting pipe 3 is connected to the inlet A of the gas-liquid separator II13, the gas outlet C1303 of the gas-liquid separator II13 is connected to the inlet A1401 of the electromagnetic three-way valve III14, the outlet B of the electromagnetic three-way valve III14 is connected to the inlet of the return pipe 15, the outlet of the return pipe 15 is connected to the return air port 701 of the compressor 7, and the return air pipe 15 is coiled on the outer casing of the compressor 7. The above circuit forms the main circulation circuit of the heat carrier.

[0083] like Figure 7 、 13 As shown, the gas outlet C903 of the gas-liquid separator I9 is ​​connected to the liquid outlet B1302 of the gas-liquid separator II13 through a mixing chamber 17. The gas outlet C903 of the gas-liquid separator I9 is ​​connected to one inlet of the mixing chamber 17 through a connecting pipe 16. The other inlet of the mixing chamber 17 is connected to the liquid outlet B of the gas-liquid separator II13 through a connecting pipe 16. The outlet of the mixing chamber 17 is connected to the pipeline between the gas-liquid separator II13 and the electromagnetic three-way valve III14 through a connecting pipe 16. Each of the three connecting pipes 16 is equipped with a one-way valve 18 to prevent the heat carrier from flowing back due to pressure difference, thereby forming a first auxiliary branch for the heat carrier. The beneficial effects of the first auxiliary branch are as follows:

[0084] On the one hand, during the operation of the prevention and control system, the residual gaseous heat carrier after the heat carrier in the roadbed heating pipe releases heat and condenses is separated by gas-liquid separator I9 and can be directly mixed with the residual liquid heat carrier after evaporation and absorption in the foundation 5 heat collecting pipe, separated by gas-liquid separator II13. Leveraging the high temperature and high pressure of the gaseous heat carrier separated by gas-liquid separator I9, the low-temperature and low-pressure liquid heat carrier separated by gas-liquid separator II13 is directly vaporized and enters the main circulation of compressor 7, avoiding damage caused by "liquid hammer" in the compressor. On the other hand, during compressor shutdown, the pressure balance between the high-pressure and low-pressure sides of the heating component can be accelerated, reducing the pressure differential resistance when the compressor is restarted, which is conducive to quickly entering normal operation.

[0085] The compressor superheat rapid increase component includes a return air pipe 15 and a bypass pipe 19. The compressor superheat rapid increase component is divided into a passive part and an active part. The passive part refers to the return air pipe 15 in the main circulation loop of the heating component; the active part refers to: the bypass pipe 19 and the heating jacket 20 outside it. Figure 6 、 9 As shown, bypass pipe 19 is connected as follows: its inlet is connected to auxiliary port C803 of electromagnetic three-way valve I8, and its outlet is connected to auxiliary port C1403 of electromagnetic three-way valve III14, forming a second auxiliary branch for the heat carrier. Its operating principle is to return the refrigerant discharged from the compressor through the bypass pipe to the return air pipe, where it re-enters the compressor, thereby increasing the return air temperature and, in turn, the compressor superheat. The beneficial effects of this second auxiliary branch are as follows:

[0086] At the initial stage of compressor startup, the bypass pipe is opened to suppress the heat carrier flow and heat dissipation on the high-pressure side of the main circuit of the heating cycle. Assisted by electric heating compensation, the problem of the heating component being unable to quickly establish compressor superheat and the startup taking too long due to the low ambient temperature is solved.

[0087] The bypass pipe 19 is constructed from a copper tube with an outer diameter of 16.0 mm and a wall thickness of 1.0 mm. The bypass pipe 19 is spirally shaped within the heating jacket 20. The heating jacket 20 is rated for 50W and a heating temperature of 40°C. The heating jacket and the solenoid valves at both ends of the bypass pipe open and close in tandem. Compared to other connecting pipes and the return air pipe, the bypass pipe has the largest diameter to reduce the extended resistance to the gaseous heat carrier's migration, allowing it to quickly form a closed bypass branch with the compressor, quickly establishing the required superheat and shortening compressor startup time. The bypass pipe is threadedly connected to the electromagnetic three-way valves I and III, allowing for flexible disassembly and installation for ease of installation and maintenance.

[0088] The compressor exhaust temperature balance adjustment component includes an electromagnetic flow valve 21 and a capillary tube 22. Figure 13As shown, the electromagnetic flow valve 21 is arranged on the capillary tube 22, and the electromagnetic flow valve 21 is arranged at the inlet end of the capillary tube 22. The inlet of the electromagnetic flow valve 21 is connected to the auxiliary port C1103 of the electromagnetic three-way valve II11, and the outlet of the electromagnetic flow valve 21 is connected to the inlet of the capillary tube 22. The outlet of the capillary tube 22 is connected to the heat carrier injection port 703 of the compressor 7, forming a third auxiliary branch of the heat carrier. Its working principle is: the liquid heat carrier in the liquid storage tank is directly diverted to the compression chamber of the compressor through the electromagnetic flow valve, increasing the heat carrier inside the compressor, which helps to solve the problem of excessively high exhaust temperature of the compressor caused by low vaporization rate of the heat carrier inside the foundation heat collecting pipe in extremely cold environments, small return air volume of the compressor, or even empty pumping. The beneficial effects of the third auxiliary branch are as follows:

[0089] The combination of an electromagnetic flow valve and a capillary tube provides both flow and phase regulation capabilities, enabling flexible implementation of both jet enthalpy increase and liquid injection cooling based on compressor status. The principle is that, depending on the compressor exhaust temperature, the electromagnetic flow valve controls the heat transfer flow, while the capillary tube controls the phase of the heat transfer agent as it enters the compressor. Specifically, by adjusting the diameter and length of the capillary, when the diversion flow of the heat carrier is small, the heat carrier will be completely vaporized after passing through the capillary, which is "jet enthalpy increase", which helps to directly increase the mass flow of the heat carrier in the main cycle, thereby increasing the heating capacity, and indirectly reducing the exhaust temperature and compression ratio of the compressor, improving the operating state of the compressor; when the diversion heat carrier increases, the heat carrier will become a gas-liquid mixture after passing through the capillary, which plays a role in increasing the return air volume to the compressor and the liquid vaporization heat absorption and cooling; when the diversion heat carrier continues to increase, the proportion of liquid heat carrier further increases, which is "liquid spray cooling", which plays a role in quickly cooling the compressor, and gradually increases the control intensity of the compressor exhaust temperature and compression ratio.

[0090] During specific production, the electromagnetic flow valve 21 regulates the flow rate within a range of 1 / 200 to 1 / 20 of the heat carrier charge per minute. The capillary tube is a copper tube with an outer diameter of 3.0 mm and a wall thickness of 0.5 mm. The capillary tube length, measured in cm, is 1 / 5 of the rated power of the compressor. For example, if the rated input power of the compressor is 200 W, the capillary tube length is 40 cm.

[0091] like Figure 5As shown, the return air pipe 15 is a copper tube with an outer diameter of 10.0 mm, a wall thickness of 1.0 mm, and a length of 2.5 m. The return air pipe is spirally coiled around the compressor casing. Its working principle is: before the gaseous heat carrier from the foundation heat collection pipe enters the compressor inlet, it further absorbs heat from the compressor casing, thereby increasing the gas temperature. The beneficial effect of the return air pipe 15 is that it utilizes the main circulation loop of the heating component without adding additional control links, and can continuously increase the superheat of the compressor return air port and reduce the temperature of the power unit such as the motor inside the compressor, thereby preventing the compressor exhaust temperature from being too high and the compression ratio from being too large. In fact, it is the passive part of the compressor superheat rapid improvement component of the present invention.

[0092] During the specific design, the compressor 7 adopts a fully enclosed single-type piston compressor with a rated input power of 100 to 600W; its characteristics are simple structure, small amount of lubricating oil consumption, long tolerance time to overload, light load and no-load, and better adaptability to extremely cold environments and railway line side vibration environments.

[0093] The gas-liquid separator I9 is ​​a gravity-sedimentation type separator, primarily designed for degassing. This separates the gaseous heat carrier as it enters the liquid storage tank, preventing the liquid heat carrier from carrying gas and affecting the throttle pressure reduction and low-pressure side pressure in the main circulation loop of the heating component, thereby ensuring the gasification and heat absorption efficiency of the heat carrier on the low-pressure side.

[0094] Gas-liquid separator II13 is a baffle separation type separator with liquid removal as its main function. The purpose is to separate the liquid heat carrier in the return gas to avoid liquid in the return gas and cause liquid hammer damage to the compressor.

[0095] The liquid storage tank 10 is an inverted conical tank, which serves to adjust the heat transfer agent's redundancy and maintain the required pressure for the heat transfer agent to flow out of the liquid storage tank. The liquid storage tank volume is 1.5 times the liquid heat transfer agent filling volume.

[0096] The throttle 12 uses an electronic expansion valve, which continuously and precisely adjusts the expansion valve opening and the heat transfer agent flow rate, improving the thermal system's performance under variable operating conditions. The electronic expansion valve is selected based on the maximum heat transfer agent flow rate of the compressor at a 70% opening. The combination of a liquid storage tank and an electronic expansion valve offers the advantage of eliminating the need for all injected heat transfer agent to participate in the heating cycle. Instead, the electronic expansion valve allows for flexible regulation of the heat transfer agent circulation based on the target heating capacity and temperature.

[0097] The components of the heating assembly's main circulation loop are connected by welded copper tubing with an outer diameter of 8.0mm and a wall thickness of 1.0mm. These connections are non-detachable and designed to enhance the equipment's stability against vibrations from the roadbed. These tubing is mounted within high-density, insulated rubber-plastic tubing with an outer diameter of 30mm and an inner diameter of 8mm to minimize heat loss along the heating loop in extremely cold climates.

[0098] The heat carrier selected is the medium-high temperature heat carrier R134a, which has a boiling point of -26.1°C and a critical temperature of 101.1°C. The advantage of this system for the prevention and control of roadbed frost heave disease is that the heat exchange temperature can be adjusted independently by adjusting the pressure on the low-pressure and high-pressure sides of the main circulation loop of the heating component. The heat absorption temperature of the geothermal heat collecting pipe (the evaporation temperature at the middle position) is generally set at -10 to -20°C. In extreme cases, it can be reduced to about -25°C, ensuring the collection efficiency of the low-grade geothermal energy by the heating component in extremely cold environments. The target heating temperature of the roadbed heating pipe is T 0 (compressor exhaust temperature) is generally set between 60°C and 80°C, but can be raised to approximately 100°C in extreme cases to ensure timely heating and frost heave prevention for the roadbed. The two are negatively correlated. When the throttle opening is smaller, that is, the heat transfer medium circulation volume is lower, the geothermal heat collector pipe heat absorption temperature is lower, the compressor exhaust temperature is higher, but the heating capacity is lower. When the throttle opening is gradually increased, that is, the heat transfer medium circulation volume increases, the geothermal heat collector pipe heat absorption temperature gradually rises, the compressor exhaust temperature gradually decreases, but the heating capacity gradually increases.

[0099] The method for determining the R134a charge level is based on an empirical approach based on comprehensive considerations during equipment trial production and application, taking into account the volume of the heating component's main circulation loop and the compressor's maximum exhaust volume. The value is 3.5 times the compressor's rated input power. For example, if the compressor's rated input power is 200W, the charge level is 700g.

[0100] During operation, the compressor exhaust port 702, heat supply pipe 2, gas-liquid separator I9, and liquid storage tank 10 represent the high-pressure side, operating within a pressure range of 1.2 to 1.8 MPa. The compressor return port 702, gas-liquid separator II13, heat collection pipe 3, and throttle 12 represent the low-pressure side, operating within a pressure range of 150 to 250 kPa. The operating principle is that the heat carrier, driven by the compressor, repeatedly completes a closed cycle of compression - condensation and liquefaction - throttling and pressure reduction - evaporation and vaporization - compression. This utilizes the compressor's work to achieve efficient heat conversion, while the heat carrier's latent heat of phase change enables efficient heat collection and transfer. Condensation and liquefaction, and evaporation and vaporization, respectively, provide heat to the roadbed and absorb heat from the subgrade, corresponding to the heat supply pipe located on the roadbed and the heat collection pipe located on the subgrade.

[0101] When used in extremely cold climates, the primary goal of these ground-source heat pump systems is to ensure the safe operation of the compressor. The first evaluation indicator for compressor operation is the absorption superheat, which has a reasonable range of 5 to 8°C. This is calculated as the difference between the compressor suction temperature and the evaporator inlet temperature. The first challenge facing ground-source heat pump systems in extremely cold environments is excessively low suction superheat during startup. This can cause excessively low compressor return air temperatures, low return air volumes, or even dry air extraction, preventing the compressor from operating normally.

[0102] The second evaluation indicator of the compressor's operating status is the exhaust gas temperature superheat, and its reasonable range is 0 to 20°C. The calculation method is the difference between the compressor exhaust temperature and the exhaust gas temperature target value. The second problem faced by the road-based heat pump system in severe cold environments is that the exhaust gas superheat is too high during operation, resulting in high-temperature alarms in the compressor, carbonization of the lubricating oil, destruction of the oil film, and damage to the entire machine, and the normal state is maintained for a short time. The main reason for the high exhaust gas temperature is that the compressor return air volume is too low in the extremely cold environment, and the heat dissipation rate of the motor is low when lightly loaded or no-loaded, resulting in deterioration of the lubricating oil inside the compressor, destruction of the oil film, and damage to the motor.

[0103] The third evaluation indicator of the compressor's operating status is the compression ratio, which refers to the ratio of the compressor's exhaust pressure to its return pressure. The reasonable range of the compression ratio is 3 to 8. When the heat carrier return air volume is too low, the compression ratio is relatively small, which is called light load or no load. This is the main problem of the roadbed-based source heat pump system caused by extremely cold environments. When the heat carrier return air volume is large, the compression ratio is relatively large, which is called overload. It is caused by the throttle opening being too large and the poor heat dissipation of the roadbed heating pipe. The third problem faced by roadbed-based source heat pump devices in extremely cold environments is that the heat carrier flow rate is not adjusted to match the actual heating demand of the roadbed, resulting in excessive energy consumption of the compressor.

[0104] In a specific embodiment of the present invention, Figure 4 As shown, the control assembly includes a PLC controller 27 and a control panel 28. The temperature sensor, pressure sensor, displacement sensor, throttle 12, electromagnetic three-way valve I8, electromagnetic three-way valve II11, electromagnetic three-way valve III14, heating jacket 20, and electromagnetic flow valve 21 are all connected to the PLC controller 27. The PLC controller 27, compressor 7, gas-liquid separator I9, and gas-liquid separator II13 are all connected to the control panel 28. The PLC controller 27 is used to store and execute logical operations and operating instructions. It is connected to the throttle, electromagnetic three-way valve, electromagnetic flow valve, electric heating jacket, temperature sensor, pressure sensor, and displacement sensor. The connection method is that the aforementioned components are integrated into a terminal block, which is then connected to the PLC controller. The control panel 28 includes a ground source heat pump operation mode setting area and a compressor operation status adjustment area. The PLC controller is connected to the control panel. Preferably, the control panel adopts an HMI configuration screen.

[0105] In a specific embodiment of the present invention, Figure 10-12 As shown, the heat collecting pipe 3 includes a pipe body 29 and a protective cover 30 at its end. The pipe body 29 is composed of an outer sleeve 31 and a base pipe 34 from the outside to the inside. The inner cavity of the base pipe 34 is filled with heat storage material 35. The outer surface of the base pipe 34 is spirally wound with a heat carrier circulation pipe 33. A heat-conducting mortar 32 is filled between the base pipe 34 and the outer sleeve 31, and the heat carrier circulation pipe 33 is immersed in the heat-conducting mortar 32. The structures of the heat supply pipe 2 and the heat collecting pipe 3 are the same.

[0106] During the specific production, the outer sleeve 31 adopts a 201 stainless steel pipe with an outer diameter of 114mm and a wall thickness of 2mm. Burying it in the stress working area of ​​the roadbed can also ensure the roadbed bearing performance requirements. At the same time, the buried structure is corrosion-resistant and ensures long-term durability.

[0107] The heat-conducting mortar 32 adopts a metal-based heat-conducting mortar with a thermal conductivity of 2.0 to 2.5 W / (m·K). The beneficial effect is that, in terms of the heat transfer path, the thermal conductivity of the roadbed heating pipe and the foundation heat collecting pipe is slightly higher than the thermal conductivity of the roadbed filler (generally 0.5 to 2.0 W / (m·K)). On the one hand, it is conducive to maintaining coordinated heat transfer performance with the soil, maintaining a continuous temperature gradient during the heat transfer process, and preventing the heat transfer condensation rate of the heat carrier circulation pipeline from being low and the roadbed heating effect from being poor; on the other hand, it prevents the large difference in thermal conductivity between the pipe and the soil, which leads to the accumulation of hot and cold and overflow loss at the contact interface.

[0108] The heat transfer agent circulation pipe 33 is a copper tube with an outer diameter of 6.0 mm and a wall thickness of 0.6 mm, spirally wound around a PVC-based pipe. The length is determined as follows: the base length of the heat transfer agent circulation pipe for the ground-based heat collection pipe is 15 m, which is then increased by 1 / 20 of the rated input power of the compressor. For example, a compressor with a rated input power of 300 W corresponds to a base length of 30 m for the ground-based heat collection pipe. This design aims to shorten the heat dissipation length of the roadbed heating pipe, which helps lower the overall evaporation temperature and improve the heat absorption efficiency of the ground-based heat energy. The base length of the heat transfer agent circulation pipe for the roadbed heating pipe is 20 m, which is then increased by 1 / 10 of the rated input power of the compressor. For example, a compressor with a rated input power of 300 W corresponds to a base length of 50 m for the ground-based heat collection pipe. This design aims to increase the heat dissipation length of the roadbed heating pipe, effectively dissipating heat, and improving the overall circulation efficiency of the heat pump and the anti-freeze effect of the roadbed heating.

[0109] The base pipe 34 is a steel mesh skeleton composite PVC pipe with an outer diameter of 75mm, which serves to fix and support the copper pipe of the heat carrier circulation pipeline; the heat storage material 35 is made of silt or sand with a moisture content of 20% to 30%. The purpose is that when the heating component stops running, the foundation heat collection pipe can continue to collect geothermal energy by relying on the residual heat collection temperature gradient, thereby improving the heat collection conditions when the heat pump is restarted; the roadbed heating pipe can continue to supply heat to the roadbed by relying on the residual heat supply temperature gradient, thereby improving the ductility of the heating performance of the heating component and providing conditions for compressor shutdown protection.

[0110] When making specific Figure 4 As shown, the cabinet 6 includes a cabinet body 602 and a base 601 at the bottom thereof, the front side of the cabinet body 602 is provided with a cabinet door that can be opened and closed, and the interior is divided into three layers by two parallel support plates in the middle, the two support plates are an upper support plate 603 and a lower support plate 604, and the two sides of the upper support plate 603 and the lower support plate 604 are respectively slidably matched with the guide rails on the inner wall of the cabinet body 602, which is convenient for installation and disassembly; an upper shield plate 605 and a lower shield plate 606 arranged vertically on the inner side of the cabinet door are provided, and the upper shield plate 605 and the lower shield plate 606 are arranged on the outer side of the guide rail, and the upper support plate 603 is provided between the upper shield plate 605 and the lower shield plate 606; the control component is provided on the upper shield plate 605, and a left window 607 and a right window 608 are respectively provided on the left and right side walls of the cabinet body 602, and the left window 607 and the right window 608 are correspondingly provided on both sides of the lower shield plate 606. Upper shields 605 and lower shields 606 shield the components on the upper support plate 603 and lower support plate 604, preventing dust from entering and affecting equipment operation. A weather-resistant stainless steel cabinet was selected for its dimensions, measuring 50cm (length x width x height) (50cm x 50cm x 50cm). The upper and lower support plates, upper and lower shields, and the cabinet are assembled, allowing for flexible disassembly and assembly.

[0111] like Figure 14 、 15 As shown in Figures 1 and 16, the compressor 7, electromagnetic three-way valve I8, electromagnetic three-way valve II11, electromagnetic three-way valve III14, liquid storage tank 10 and mixing chamber 17 are arranged on the upper support plate 603, and the bypass pipe 19, electromagnetic flow valve 21, capillary tube 22, gas-liquid separator I9, throttle 12 and gas-liquid separator II13 are arranged on the lower support plate 604; the control component is arranged on the upper shield plate 605.

[0112] The specific assembly process of the above-mentioned ground source heat pump device is as follows:

[0113] Step 1: Install and fix the components on the upper support plate, lower support plate and upper shield plate respectively.

[0114] Step 2: Push the upper support plate into the upper guide rail inside the cabinet and push the lower support plate into the lower guide rail inside the cabinet.

[0115] Step 3: Connect the inlet and outlet of the compressor superheat rapid improvement component on the lower support plate to the auxiliary port C of the electromagnetic three-way valves I and III, and connect the inlet and outlet of the compressor exhaust temperature equalization adjustment component to the auxiliary port C of the electromagnetic three-way valve II and the heat carrier injection port of the compressor respectively.

[0116] Step 4: Extend the two ports of the upper support plate connected to the foundation heat collection pipe, namely the outlet of the throttle 12 and the inlet A1301 of the gas-liquid separator II, to the left window of the lower shield plate; extend the two ports of the upper support plate connected to the roadbed heating pipe, namely the outlet B802 of the electromagnetic three-way valve I and the inlet A901 of the gas-liquid separator I, to the right window of the lower shield plate, so as to be connected to the foundation heat collection pipe and the roadbed heating pipe respectively.

[0117] Step 5: Connect the wiring terminals to the PLC controller and secure the upper shield to the end of the cabinet rail. This completes the heating unit and allows it to be transported to the site for use.

[0118] The heating components are installed in separate units within the cabinet. The heating unit utilizes a split structure, which allows for efficient integration and disassembly, and is easy to assemble, repair, replace, and upgrade. The heating component is the core functional part of the ground-source heat pump unit. The compressor superheat rapid increase component and the compressor exhaust temperature equalization adjustment component are removable and freely combinable auxiliary structures. They can be integrated with the heating component into a complete product before shipment, or they can be added as reinforcements to heating units already installed in the field.

[0119] Compared to existing technologies, this invention adds a compressor superheat rapid increase component and a compressor exhaust temperature equalization control component to the traditional ground-source heat pump heating cycle components, enabling the heating unit to adapt to severe cold climates. These components prevent slow startup times caused by insufficient compressor suction superheat during startup, and low compressor return air volume and high exhaust temperatures caused by poor ground temperature and energy conditions. This ensures the operational reliability and longevity of the ground-source heat pump system, improving its weather resistance. The heating unit utilizes a two-layer modular structure, resulting in a modular, unitized design that facilitates assembly, disassembly, maintenance, replacement, and upgrades. It also incorporates a mechatronic control component with operational status monitoring and regulation, resulting in a high level of automation. A calculation and design method is provided for key parameters, including the layout parameters of the subgrade heating pipes, the heating capacity of the heating unit, and the layout parameters of the subgrade heat collector pipes. This method achieves quantitative matching to subgrade frost heave scenarios and improves reliability. Overall, this solution addresses the technical issues of poor weather resistance and operational reliability faced by subgrade ground-source heat pump systems operating in extremely cold climates.

[0120] The present invention also provides a method for preventing and controlling railway subgrade frost heave disease that is adaptable to severe cold climates, comprising the following steps:

[0121] 1) Assemble and install the above-mentioned prevention and control system, design the layout parameters of the heating pipes and collector pipes and the heating capacity of the heating units;

[0122] The above-mentioned ground source heat pump device is installed in the frost heave diseased area of ​​the roadbed. The specific construction contents are as follows:

[0123] Item 1: On-site installation of roadbed heating pipes.

[0124] The layout is to arrange the pipes horizontally at regular intervals within the frost heave layer of the roadbed, perpendicular to the line's direction. Parameters include main body length, vertical burial depth (the distance between the centerline of the roadbed heating pipe and the top surface of the roadbed), and longitudinal spacing. These parameters are calculated and designed based on the specific roadbed frost heave scenario.

[0125] The installation plan is as follows: Step 1, before entering the construction site, prepare the stainless steel outer casing and heat transfer agent circulation pipeline in advance, and complete the filling and sealing of the heat storage material in the PVC base pipe. Step 2, enter the construction site and implant the stainless steel outer casing. For the operating roadbed, use the down-the-hole drill or spiral drill mechanical drilling method. If the hole collapses seriously during the drilling process, the follow-the-pipe drilling method is used to ensure the safety of the line train operation; for the newly built roadbed, use the method of direct burial at the corresponding burial depth by mechanical or manual grooving. Step 3, insert the heat transfer agent circulation pipeline prepared in advance into the stainless steel outer casing.

[0126] Item 2: On-site installation of foundation solar collector tubes.

[0127] The layout is to install the heating pipes vertically in the foundation outside the slope foot, aligned with the location of the roadbed heating pipes. The distance from the slope foot should be maintained at least 3 meters to prevent interference with the roadbed during drilling and heat collection. Layout parameters include the height of the foundation heat collection pipes and the buried depth of the top of the heat transfer medium circulation pipes. Layout parameters are calculated and designed based on the heating performance of the ground-source heat pump and the distribution of ground temperature energy.

[0128] The installation plan is similar to the roadbed heating pipe, the difference is that whether it is an operating roadbed or a newly built roadbed, the stainless steel outer casing is implanted by mechanical drilling.

[0129] Item 3: On-site installation of heating unit.

[0130] The layout is: arranged at regular intervals on the foundation at the toe of the roadbed. The design parameter for the heating unit is the rated heating capacity, calculated and designed based on the specific roadbed frost heave scenario and the roadbed heating pipe layout plan. Once the rated heating capacity of the ground-source heat pump system is determined, the selection methods for various components, such as the compressor, are well-known in the industry and will not be elaborated on here.

[0131] The installation plan is as follows: Step 1: Prepare the heating unit before construction begins. Step 2: Once on site, level the ground and pour a concrete foundation measuring 70cm x 70cm x 20cm. Step 3: Secure the cabinet base using expansion bolts, ensuring the base is level to ensure proper operation of the compressor's internal moving parts. Step 4: Place the cabinet on the base.

[0132] Item 4: Commissioning of ground source heat pump device.

[0133] Step 1: Connect the main circulation loop of the heating component. Connect the heating unit, foundation heat collector, and roadbed heating pipe according to the aforementioned arrangement. Exposed connecting pipes are wrapped with high-density rubber-plastic insulation tubing, which is protected by anti-aging PVC tubing. Step 2: Turn on the power supply and fully open the throttle, three-way solenoid valve, and electromagnetic flow valve. Test for proper operation, then close auxiliary port C of three-way solenoid valve II. Step 3: Use a vacuum pump to evacuate the interior of the heating component at the compressor's heat carrier inlet. Step 4: Inject the rated mass of liquid heat carrier into the heating unit's piping through the heat carrier inlet. Step 5: Restore the threaded connection between the compressor's heat carrier inlet and the capillary outlet. Step 6: Conduct a trial run of the heating unit, setting relevant parameters and observing the operating status via the control panel until normal operation is achieved. Step 7: Inject thermal conductive mortar into the roadbed heating pipe and foundation heat collector.

[0134] The design of the above-mentioned ground source heat pump device includes the following contents:

[0135] The first item is the calculation and design of heating pipe layout parameters;

[0136] The calculation and design method for the vertical burial depth of heating pipes within the roadbed is as follows: through on-site exploration and monitoring of frost heave disease areas on the roadbed, the harmful freezing depth of the roadbed is determined, which is the vertical burial depth of the roadbed heating pipes. The beneficial effect of this value selection scheme is to form a thermal barrier layer at the harmful freezing depth. First, it prevents the roadbed freezing depth from continuing to increase in severe cold weather, thus preventing frost heave disease. Second, it allows the roadbed to freeze above the harmful freezing depth, reducing ineffective heat output. Third, it increases the soil temperature below the harmful freezing depth, i.e., the heat storage capacity, thereby increasing the roadbed's potential to resist extreme cold snaps and other extreme weather conditions. At the same time, it is necessary to ensure that the minimum vertical burial depth of the roadbed heating pipes is 40 cm, in order to avoid the concentrated distribution area of ​​additional stress from train loads on the roadbed.

[0137] The calculation and design method of the longitudinal spacing of the heating pipes in the roadbed along the railway direction is: based on the determination of the buried depth of the roadbed heating pipes, the heat-affected radius calculation formula, as shown in formula (1), is used to calculate the increase law of the heat-affected radius of the roadbed heating pipes over time. Take the time corresponding to 2 days and 48 hours R The value is the expected prevention and control range of a single roadbed heating pipe facing the frost heave disease, so the longitudinal spacing between adjacent roadbed heating pipes is 2 R The heat affected radius of the heating pipe is calculated as follows:

[0138] (1)

[0139] Where, T 0 is the outer wall temperature of the heating pipe, which is equal to the set value of the compressor exhaust temperature, °C; T f is the target temperature of the roadbed filler, which is generally taken as the freezing temperature of the filler, °C; Ts is the lowest daily average temperature of the ordinary roadbed during the freezing period with a harmful freezing depth, °C; K s is the correction coefficient of the roadbed filler, which is taken as the compaction coefficient of the roadbed, that is, when the roadbed is poorly compacted, the heat affected radius decreases accordingly; a is the filler thermal diffusivity, m 2 / h; τ is time, h; H 1 is the harmful freezing depth of the roadbed, m;

[0140] The calculation and design method for the length of the heating pipe body in the roadbed is: based on the determination of the buried depth of the heating pipe in the roadbed, the length of the heating pipe is calculated. Referring to the standard track gauge of 1.435m in my country, the heating pipes on both sides are laid directly under the rails on both sides of the center of the railway line. The length of the heating pipe is calculated as follows:

[0141] (2)

[0142] Where,k is the width-to-height ratio of the roadbed slope; b is the shoulder width, m; B The width of the trackbed of a single-track railway or the width of the trackbed of the upline or downline of a double-track railway, in m;

[0143] The second item is the calculation and design of the heating capacity of the heating unit;

[0144] The heating capacity of each heating unit is calculated as follows:

[0145] (3)

[0146] Where, λ 1 is the surface convection heat transfer coefficient, W / (m 2 ℃); h is the roadbed height, m; T a is the daily average temperature; Δ H is the growth rate of freezing depth of ordinary roadbed, m / s; ρ is the density of the roadbed filler, kg / m 3 ; c is the specific heat capacity of the roadbed filler, J / (kg·℃);

[0147] The third item is the calculation and design of the layout parameters of the heat collecting tubes in the foundation;

[0148] The method for determining the buried depth of the top of the heat transfer medium circulation pipeline of the foundation heat collecting pipe is: through on-site exploration and monitoring of the foundation near the frost heave disease site of the roadbed, the maximum freezing depth of the foundation is determined, which is the buried depth of the top of the heat transfer medium circulation pipeline. H 2.

[0149] The calculation of the body height of the foundation heat collecting tube is as follows:

[0150] (4)

[0151] Where H2 is the buried depth of the top of the heat transfer medium circulation pipeline, which is the maximum freezing depth of the natural surface, m; d is the equivalent heat absorption diameter of the stainless steel outer casing for geothermal energy, m; λ 2 is the heat transfer coefficient of the contact interface between the stainless steel outer casing and the foundation soil, W / (m 2 ℃); T e is the average temperature of the heat transfer medium circulation pipeline of the ground-based heat collecting tube, ℃; T g It is the average ground temperature below the maximum freezing depth of the foundation.

[0152] Start the ground source heat pump device and enter the design parameters of the above heating components on the control panel; power the compressor to start, and open all valves on the main circulation loop at the same time, while the valves on the second auxiliary branch of the compressor superheat rapid increase component and the third auxiliary branch of the compressor exhaust temperature equalization adjustment component remain closed.

[0153] 2) At a fixed interval of 30 minutes, the measured values ​​of two temperature sensors arranged on the roadbed and two displacement sensors arranged on the track are sensed and displayed.

[0154] 3) The PLC controller calculates the differential frost heave deformation of the track structure, that is, the amplitude of the track's unevenness, and obtains the subgrade freezing depth and the average temperature of the harmful freezing depth range based on linear interpolation of the subgrade temperature sensor.

[0155] 4) When the differential frost heave deformation is less than the track height irregularity management limit specified in the "Rules for Repair of Conventional Railway Lines" (TG / GW102) or the "Rules for Repair of High-Speed ​​Railway Lines" (National Railway Equipment Supervision Regulation

[2023] No. 15), it indicates that the prevention stage of frost heave disease is in progress. The operating mode control plan for the ground-source heat pump device is as follows:

[0156] Based on the weather forecast and the measured data in step 2), the PLC controller calculates the required heating capacity at a fixed interval of 30 minutes. The PLC controller then calculates the required heat carrier flow rate and the corresponding throttle opening based on the required heating capacity (i.e., Q calculated by formula (3)).

[0157] The heat transfer flow rate is calculated by dividing the required heating capacity of a single heat pump by the heat transfer agent's latent heat of phase change. The latent heat of phase change for R134a is 215.6 kJ / kg. The throttle opening is calculated as the ratio of the heat transfer flow rate to the maximum allowable flow rate.

[0158] 5) When the differential frost heave deformation exceeds the track height irregularity management limit specified in the "Rules for Repair of Conventional Railway Lines" (TG / GW102) or the "Rules for Repair of High-Speed ​​Railway Lines" (National Railway Equipment Supervision Regulation

[2023] No. 15), it indicates that the post-disaster rapid remediation stage of frost heave damage has begun. The operating mode control plan for the ground-source heat pump device is as follows:

[0159] The throttle opening is opened to 70% until the differential frost heave deformation of the track is reduced to within the management limit, and then the operation mode of step 4 is restored.

[0160] The beneficial effects of the above design are: compressor selection and heat carrier filling are carried out according to the maximum load. Through the on-site measurement results of roadbed temperature and deformation, the throttle opening and heat carrier flow rate can be flexibly adjusted according to different roadbed frost heave disease sections, or the disease degree of the same frost heave disease section at different times, so as to achieve dynamic matching between the heat pump operation mode and the degree of roadbed frost heave disease, and solve the problems of large heat overflow loss and compressor energy consumption when the conventional control method is based solely on roadbed temperature.

[0161] In step 4), the operating mode of the ground source heat pump device is adjusted by the operating state of the compressor. The control process and adjustment logic are:

[0162] 1) Sense and display the three temperature sensors and two pressure sensors placed in the heating unit at a fixed interval of 10 minutes;

[0163] 2) PLC controls the calculation of three compressor evaluation indicators, including compression ratio, suction superheat, and discharge superheat;

[0164] 3) Based on the compressor evaluation index, execute the control commands for the compressor superheat rapid increase component and the compressor exhaust temperature balance adjustment component. The specific plan is as follows:

[0165] ① When the indicated suction superheat is below 5°C, the PLC controls the valve opening of the compressor superheat rapid increase assembly. ② When the indicated compression ratio is greater than 8, the PLC controls the electromagnetic flow valve of the compressor discharge temperature equalization adjustment assembly to release 1 / 200 of the total heat transfer agent charge per minute for air injection to increase heat enthalpy. ③ When the indicated discharge superheat is greater than 20°C, the PLC controls the electromagnetic flow valve of the compressor discharge temperature equalization adjustment assembly to release 1 / 100 of the total heat transfer agent charge per minute for liquid injection cooling. The latter takes precedence over the former. These operations are all controlled at fixed 10-minute intervals, with the opening and closing of the compressor superheat rapid increase assembly and the compressor discharge temperature equalization adjustment assembly adjusted according to the corresponding compressor operating status indicators.

[0166] The beneficial effect of this design is that it can accurately adjust the action of each control valve according to the real-time status of the compressor, improve the problems of difficulty in establishing suction superheat and long startup time during the startup phase of the compressor in severe cold climates, as well as low vaporization rate of the foundation collector pipe, small compressor return air volume and high exhaust temperature during normal operation, comprehensively improve the starting performance and operating performance of the compressor, and enhance low-temperature heating performance.

[0167] 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 aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A railway subgrade frost heave disease prevention and control system adapted to severe cold climates, characterized by: The prevention and control system includes several groups of ground-source heat pump devices spaced apart along the length of the railway subgrade. The ground-source heat pump devices include a heating unit, a heat supply pipe, a heat collection pipe, and a detection assembly. The heat collection pipe is connected to the heat supply pipe via the heating unit. The heating unit is located on the surface of the foundation at the foot of the subgrade. The heat supply pipe is laid horizontally in the frost heave development layer of the subgrade. The heat collection pipe is located in the lower stabilization layer of the foundation on both sides of the subgrade. The detection assembly includes a temperature sensor, a pressure sensor, and a displacement sensor. Temperature sensors are installed in the roadbed, in the middle of the heat collecting pipe, and on the pipeline of the heating unit, respectively for monitoring the harmful freezing temperature of the roadbed and the temperature of the heat carrier in the pipeline; the compressor return port and the compressor exhaust port of the heating unit are both equipped with pressure sensors for monitoring the suction and exhaust pressures of the compressor; the displacement sensor is installed at the waist of the railway track to detect the deformation of the track. The heating unit, temperature sensor, pressure sensor, and displacement sensor are all connected to the control assembly; The heating unit includes a cabinet and a heating component. The heating component and the control component are both arranged in the cabinet. The heating component is connected to the heat supply pipe and the heat collection pipe through a pipeline. The heating component can realize the condensation and liquefaction and evaporation and gasification of the heat carrier, which are respectively used to supply heat to the roadbed and absorb heat from the foundation; The heating assembly includes a compressor, a gas-liquid separator I, a liquid storage tank, a throttle and a gas-liquid separator II. The compressor exhaust port is connected to the inlet A of the electromagnetic three-way valve I, the outlet B of the electromagnetic three-way valve I is connected to the inlet of the heating pipe, the outlet of the heating pipe is connected to the inlet A of the gas-liquid separator I, the liquid outlet B of the gas-liquid separator I is connected to the inlet of the liquid storage tank, the outlet of the liquid storage tank is connected to the inlet A of the electromagnetic three-way valve II, the outlet B of the electromagnetic three-way valve II is connected to the inlet of the throttle, the outlet of the throttle is connected to the inlet of the heat collecting pipe, the outlet of the heat collecting pipe is connected to the inlet A of the gas-liquid separator II, the gas outlet C of the gas-liquid separator II is connected to the inlet A of the electromagnetic three-way valve III, the outlet B of the electromagnetic three-way valve III is connected to the inlet of the return pipe, and the outlet of the return pipe is connected to the return air port of the compressor, thereby forming a main circulation loop of the heat carrier; The system further comprises a mixing chamber, wherein the gas outlet C of the gas-liquid separator I is connected to one inlet of the mixing chamber via a connecting pipe, the other inlet of the mixing chamber is connected to the liquid outlet B of the gas-liquid separator II via a connecting pipe, and the outlet of the mixing chamber is connected to the pipeline between the gas-liquid separator II and the electromagnetic three-way valve III via a connecting pipe; each connecting pipe is provided with a one-way valve, forming a first auxiliary branch of the heat carrier; It also includes a compressor superheat rapid improvement component, including a return air pipe and a bypass pipe, the bypass pipe is provided with a heating jacket on the outside, the inlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve I, and the outlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve III, forming a second auxiliary branch of the heat carrier; It also includes a compressor exhaust temperature balancing and regulating component, which includes an electromagnetic flow valve and a capillary tube. The electromagnetic flow valve is arranged on the capillary tube, the inlet of the electromagnetic flow valve is connected to the auxiliary port C of the electromagnetic three-way valve II, the outlet of the electromagnetic flow valve is connected to the inlet of the capillary tube, and the outlet of the capillary tube is connected to the heat carrier injection port of the compressor, forming a third auxiliary branch of the heat carrier.

2. The railway subgrade frost heave disease prevention and control system adapted to severe cold climates according to claim 1, characterized in that: The return air pipe is a copper tube with an outer diameter of 10.0 mm, a wall thickness of 1.0 mm, and a length of 2.5 m. The return air pipe is spirally coiled on the outer shell of the compressor; the bypass pipe is a copper tube with an outer diameter of 16.0 mm and a wall thickness of 1.0 mm. The bypass pipe inside the heating jacket is spiral. The rated power of the heating jacket is 50 W and the heating temperature is 40°C; the capillary tube is a copper tube with an outer diameter of 3.0 mm and a wall thickness of 0.5 mm. The length of the capillary tube is in cm, and the value is 1 / 5 of the rated power of the compressor.

3. The railway subgrade frost heave disease prevention and control system adapted to severe cold climates according to claim 1 is characterized by: The control component includes a PLC controller and a control panel. The temperature sensor, pressure sensor, displacement sensor, throttle, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, heating jacket, and electromagnetic flow valve are all connected to the PLC controller. The PLC controller, compressor, gas-liquid separator I, and gas-liquid separator II are all connected to the control panel.

4. The railway subgrade frost heave disease prevention and control system adapted to severe cold climates according to claim 1, characterized in that: The heat collecting tube comprises a tube body and a protective cover at its end. The tube body is composed of an outer sleeve and a base tube from the outside to the inside. The inner cavity of the base tube is filled with heat storage material. The outer surface of the base tube is spirally wound around the heat transfer agent circulation tube. The space between the base tube and the outer sleeve is filled with heat-conducting mortar. The heat transfer agent circulation tube is immersed in the heat-conducting mortar. The heat supply pipe and the heat collecting pipe have the same structure.

5. The railway subgrade frost heave disease prevention and control system adapted to severe cold climates according to claim 4 is characterized by: The outer sleeve is a 201 stainless steel tube with an outer diameter of 114 mm and a wall thickness of 2 mm, and the thermal conductive mortar is a metal-based thermal conductive mortar with a thermal conductivity of 2.0 to 2.5 W / (m·K); The heat transfer medium circulation pipe is a copper tube with an outer diameter of 6.0mm and a wall thickness of 0.6mm; the base pipe is a steel mesh skeleton composite PVC pipe with an outer diameter of 75mm; the heat storage material is silt or sand with a moisture content of 20% to 30%; The heat carrier is a medium-high temperature heat carrier R134a, and the charging amount of the heat carrier is in grams, which is 3.5 times the rated power of the compressor; The compressor adopts a fully enclosed single-type piston compressor with a rated input power of 100-600W; the gas-liquid separator I selects a gravity sedimentation type separator, and the gas-liquid separator II selects a baffle separation type separator; the liquid storage tank adopts an inverted cone tank body, and the throttle adopts an electronic expansion valve.

6. The railway subgrade frost heave disease prevention and control system adapted to severe cold climates according to claim 1, characterized in that: The cabinet includes a cabinet body and a base at the bottom thereof; the front side of the cabinet body is provided with a cabinet door that can be opened and closed; the interior is divided into three layers by two parallel supporting plates in the middle, the two supporting plates being an upper supporting plate and a lower supporting plate; an upper shield plate and a lower shield plate are vertically arranged on the inner side of the cabinet door; a left window and a right window are respectively provided on the left and right side walls of the cabinet body; The compressor, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, liquid storage tank and mixing chamber are arranged on the upper support plate, and the bypass pipe, electromagnetic flow valve, capillary tube, gas-liquid separator I, throttle and gas-liquid separator II are arranged on the lower support plate; the control component is arranged on the upper shield plate.

7. A method for preventing and controlling railway subgrade frost heave disease in cold weather, characterized in that: The following steps are involved: 1) Assemble and install the prevention and control system according to any one of claims 1 to 6, and design the layout parameters of the heating pipes and heat collecting pipes and the heating capacity of the heating unit; Start the ground source heat pump device and input the design parameters on the control panel of the control component; Start the compressor, open the main circulation loop at the same time, and close the second auxiliary branch of the compressor superheat rapid improvement component and the third auxiliary branch of the compressor exhaust temperature equalization adjustment component; 2) Regularly collect the measured values ​​of the temperature sensor on the roadbed and the displacement sensor on the track at a fixed interval of 10-30 minutes; 3) The PLC controller of the control component calculates the differential frost heave deformation of the track structure, that is, the amplitude of the track's unevenness, and obtains the subgrade freezing depth and the average temperature of the harmful freezing depth range based on linear interpolation of the subgrade temperature sensor; 4) When the differential frost heave deformation is less than the specified track height irregularity management limit, it indicates that the track is in the frost heave disease prevention stage. The operation mode control scheme of the ground source heat pump device is as follows: Based on the weather forecast and the measured data from step 2), the PLC controller calculates the required heating capacity and obtains the required heat transfer agent flow and the corresponding throttle opening at a fixed interval t of 10-30 minutes; The heat transfer medium flow rate is calculated by dividing the heating power of a single heat pump by the phase change latent heat value of the heat transfer medium. The throttle opening is calculated by the ratio of the heat transfer medium flow rate to the maximum allowable flow rate. 5) When the differential frost heave deformation exceeds the specified track height irregularity management limit, it indicates that the frost heave disease has entered the post-disaster rapid remediation stage; the operating mode control scheme of the ground source heat pump device is as follows: The throttle opening is opened to 70% until the differential frost heave deformation of the track is reduced to within the management limit, and then the operation mode of step 4 is restored.

8. The method for preventing and controlling railway subgrade frost heave disease in cold weather according to claim 7, characterized in that: In step 4), the operating mode of the ground source heat pump device is adjusted by the operating state of the compressor, and the adjustment logic is as follows: 1) Sense and display the temperature and pressure sensors located in the heating unit at a fixed interval of 10 minutes; 2) The PLC controls and calculates the compressor's evaluation indicators, including compression ratio, suction superheat, and discharge superheat; 3) Based on the compressor evaluation index, execute the control commands for the compressor superheat rapid increase component and the compressor exhaust temperature balance adjustment component. The specific plan is as follows: ①When the suction superheat is displayed below 5℃, the PLC controls the opening of the compressor superheat rapid increase component; ② When the displayed compression ratio is greater than 8, the PLC controls the compressor exhaust temperature equalization adjustment component to release 1 / 200 of the total heat carrier charge per minute to increase the heat transfer rate; ③ When the exhaust gas superheat is displayed to be greater than 20℃, the PLC controls the compressor exhaust gas temperature equalization adjustment component to release 1 / 100 of the total heat carrier charge per minute to perform liquid spray cooling; The operations of the above steps ①, ②, and ③ are all performed at fixed intervals of 10 minutes, and the opening and closing of the compressor superheat rapid improvement component and the compressor exhaust temperature equalization adjustment component are adjusted according to the corresponding compressor evaluation indicators.

9. The method for preventing and controlling railway subgrade frost heave disease in cold climates according to claim 7, characterized in that: In step 1), the longitudinal spacing between the heating pipes of adjacent roadbeds is 2R, and the heat affected radius of the heating pipes is calculated as follows: （1） Where, T 0 is the outer wall temperature of the heating pipe, °C; T f is the target temperature of the roadbed filler, °C; T s The lowest daily average temperature during the freezing period of the harmful freezing depth of ordinary roadbed, ℃; K s is the correction factor of the roadbed filler, which is taken as the compaction coefficient of the roadbed; a is the filler thermal diffusivity, m 2 / h; τ is time, h; H 1 is the harmful freezing depth of the roadbed, m; The railway track gauge is 1.435m. The heating pipes on both sides are laid directly below the rails on both sides of the center of the railway line. The length of the heating pipes is calculated as follows: （2） Where, k is the width-to-height ratio of the roadbed slope; b is the shoulder width, m; B The width of the trackbed of a single-track railway or the width of the trackbed of the upline or downline of a double-track railway, in m; The heating capacity of the heating unit is calculated as follows: （3） Where, λ 1 is the surface convection heat transfer coefficient, W / (m 2 ℃); h is the roadbed height, m; T a is the daily average temperature; ΔH is the growth rate of freezing depth of ordinary roadbed, m / s; ρ is the density of the roadbed filler, kg / m 3 ; c is the specific heat capacity of the roadbed filler, J / (kg·℃); The height of the heat collecting tube is calculated as follows: （4） Where H2 is the buried depth of the top of the heat transfer medium circulation pipeline, which is the maximum freezing depth of the natural surface, m; d is the equivalent heat absorption diameter of the stainless steel outer casing for geothermal energy, m; λ 2 is the heat transfer coefficient of the contact interface between the stainless steel outer casing and the foundation soil, W / (m 2 ℃); T e is the average temperature of the heat transfer medium circulation pipeline of the ground-based heat collecting tube, ℃; T g It is the average ground temperature below the maximum freezing depth of the foundation.

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