Solar refrigeration device and permafrost protection method

Abstract

The invention discloses a solar refrigeration device and a permafrost protection method, and belongs to the technical field of permafrost protection.The refrigeration device comprises a solar driving unit, an absorption type refrigeration unit and a cooling capacity transmission unit, and the solar driving unit provides a heat source for a bubble generator of the absorption type refrigeration unit and provides power for circulating flowing of a refrigerant; and a condensation section of the cold energy transmission unit is arranged in the cold storage assembly to absorb cold energy, and the cold energy is transmitted to a permafrost degeneration disease work site where the traffic infrastructure is located through a refrigeration section to protect permafrost. The green refrigeration technology is introduced into the field of traffic infrastructure from the field of building environment, the refrigeration device and the condensation section and the refrigeration section of the cooling capacity transmission unit are separately arranged according to application scenes, the function of protecting permafrost is achieved, and the scene adaptability is high; solar energy is used as a driving source, external power supply is not needed, self-driven operation is achieved, the intelligent degree is high, and green and energy-saving effects are achieved; no moving part exists, and the service life is long; installation is convenient, operation is automatic, and reliability is high.

Description

Technical Field

[0001] The invention belongs to the technical field of permafrost protection, and in particular relates to a solar refrigeration device and a permafrost protection method. Background Art

[0002] Frozen soil refers to various rocks and soils below 0℃ and containing ice. From the perspective of engineering construction and operation, frozen soil is a special type of undesirable soil. Permafrost refers to soil layers that remain frozen and unmelted for 2 years or more. Permafrost is a fragile geological body. Under the background of global warming, natural permafrost shows the phenomenon of rising temperature, melting of porous ice, shrinking or disappearing thickness and distribution range, that is, permafrost degradation. Permafrost degradation will lead to adverse geological phenomena such as thawing, thaw mudflow, and swamp wetlands. my country's Qinghai-Tibet Plateau is the world's largest low-latitude and high-altitude permafrost area, and currently has many railway transportation trunk lines. A large number of transportation infrastructure such as roadbeds, tunnels, and bridge pile foundations are directly built on permafrost layers, and their service conditions such as stability and durability are closely related to permafrost. The construction and operation process of transportation infrastructure will aggravate the degradation of permafrost. After the degradation of permafrost, the bearing capacity of the foundation is reduced, and the melting settlement deformation will cause deformation or even damage to the roadbed, tunnels, and bridge pile foundations. Statistics show that more than 80% of the damage on the Qinghai-Tibet Highway is caused by thawing of permafrost. Since its operation, the degradation and thawing of permafrost has caused a series of problems such as roadbed settlement, tilting of bridge pile foundations, and deadlock of expansion joints at the ends of beams, which have become the bottleneck of the operation and maintenance of the entire line. Therefore, how to effectively protect permafrost is the key.

[0003] Permafrost protection methods include passive insulation structures such as insulation layers and thermal barriers, as well as active cooling structures such as ventilation pipes, block layers, and heat pipes. At present, the above permafrost protection measures on the Qinghai-Tibet Railway and Qinghai-Tibet Highway can only adapt to the situation of climate warming of 1°C. In the future, if the climate warms by 1.5°C, permafrost reinforcement measures will need to be planned. It is necessary to develop more effective permafrost protection methods as soon as possible.

[0004] At present, the shortcoming of existing permafrost protection measures is that they mainly offset the thermal erosion in the warm season by increasing the cold storage in winter, but they cannot output stable cold in the warm season and have poor timeliness. The difficulty of permafrost refrigeration protection technology is that refrigeration is a reverse heat transfer process that requires external energy (electricity) to drive it. It is difficult to supply electricity along the transportation lines in permafrost areas such as the Qinghai-Tibet Plateau, which is constrained by insufficient electricity supply. If the conventional centralized refrigeration and decentralized transmission and distribution methods in the construction and industrial fields are adopted, the investment is large and the energy consumption is high, but there is currently a lack of suitable refrigeration equipment and energy supply solutions. Therefore, the specialization of refrigeration technology equipment for transportation infrastructure scenarios and energy-saving operation are the key to achieving permafrost refrigeration protection. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a solar refrigeration device and a permafrost protection method.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A solar refrigeration device, the refrigeration device comprises a solar drive unit, an absorption refrigeration unit and a cold energy transfer unit, the absorption refrigeration unit comprises a cold storage component and a bubble generator, a bubble pump, a gas-liquid separator, a condenser, a throttle, an evaporator, an absorber and a liquid storage tank which are connected in sequence and filled with a refrigerant, the liquid storage tank is then connected to the bubble generator through a main connecting pipe to form a closed circulation loop, which serves as a main circulation flow channel for the refrigerant, the cold storage component is used to store the cold energy generated by the evaporator; the electric heating component of the solar drive unit is arranged on the outer wall of the bubble generator to provide a heat source for the volatilization of the refrigerant; the condensing section of the cold energy transfer unit is arranged in the cold storage component, and the refrigeration section of the cold energy transfer unit can be placed in a degraded permafrost layer.

[0007] Furthermore, the components of the refrigerant include a refrigerant, an absorbent and a diffusant, the mass ratio of the refrigerant to the absorbent is 1:1 to 1:3, and the diffusant is an inert gas; the heating temperature of the electric heating component is between the boiling points of the refrigerant and the absorbent.

[0008] Furthermore, the refrigerant of the refrigerant is ammonia, the absorbent is distilled water, the diffusant is helium, and the filling pressure of the helium is 18 bar.

[0009] Furthermore, it also includes an auxiliary connecting pipe, which includes a first connecting pipe, a second connecting pipe and a third connecting pipe. The absorber is connected to the secondary inlet of the generator through the first connecting pipe to prevent the refrigerant from flowing back due to the excessive liquid level inside the absorber; the condenser is connected to the secondary inlet of the absorber through the second connecting pipe to allow the liquid absorbent that is not completely separated in the gas-liquid separator to enter the absorber; the evaporator is connected to the secondary inlet of the liquid storage tank through the third connecting pipe to allow the refrigerant that is not completely vaporized in the evaporator to flow into the liquid storage tank; the auxiliary connecting pipe serves as an auxiliary circulation channel for the refrigerant.

[0010] Furthermore, the solar drive unit includes a photovoltaic component, a power storage component, an electric heating component and a PLC controller. The photovoltaic component, the power storage component, the PLC controller and the electric heating component communication lines are connected in sequence. The photovoltaic component is used to convert solar energy into electrical energy. The power storage component is used to store the electrical energy generated by the photovoltaic component. The power storage component is connected to the electric heating component to provide power for the electric heating component; the PLC controller is used to control the overcharging and overdischarging of the power storage component and the start and stop of the electric heating component.

[0011] Furthermore, the absorption refrigeration unit, power storage component, electric heating component and PLC controller are all arranged in a cabinet, the photovoltaic component is arranged on the outside of the cabinet, a shield is provided on the inner side of the cabinet door, and the PLC controller is arranged on the shield; the interior of the cabinet is provided with an upper tray, a middle tray and a lower tray from top to bottom, the gas-liquid separator and condenser are arranged on the upper tray, the throttle, evaporator and cold storage component are arranged on the middle tray, and the bubble generator, bubble pump, absorber, liquid storage tank and power storage component are arranged on the lower tray; an exhaust fan is provided on the inner wall above the upper tray, and the exhaust fan is connected to the PLC controller for discharging heat emitted by the condenser; the exhaust fan is connected to the electric heating component in parallel with the power storage component; through holes are provided on the upper tray, the middle tray and the lower tray for passing through the auxiliary connecting pipe and the main connecting pipe of the liquid storage tank inlet and outlet.

[0012] Furthermore, the PLC controller is embedded with two thresholds and two commands, the two thresholds are the upper threshold and the lower threshold of the permafrost layer temperature; the two commands are respectively the first category command and the second category command, the first category command: controls the electric heating component and the exhaust fan to be powered on and run, the second category command: controls the electric heating component and the exhaust fan to be powered off and shut down; the execution basis of the two commands is as follows: When the monitoring value of the temperature sensor buried in the permafrost layer is higher than the upper limit threshold, the first type of command is executed; when the monitoring value of the temperature sensor buried in the permafrost layer is lower than the lower limit threshold, the second type of command is executed.

[0013] Furthermore, the cold energy transfer unit is a separate heat pipe, which includes a condensing section, an insulating connecting section and a refrigeration section. The insulating connecting section is arranged between the condensing section and the refrigeration section. The insulating connecting section is a flexible pipe. The condensing section and the refrigeration section are both rigid pipes. The size of the refrigeration section matches the protection depth of the permafrost layer. The interior of the separate heat pipe is filled with a heat transfer medium, and the boiling point temperature of the heat transfer medium is lower than the target temperature of permafrost protection.

[0014] The present invention also provides a permafrost protection method, which uses the above-mentioned solar refrigeration device and comprises the following steps: Step S01: Select a permafrost degradation site scenario for transportation infrastructure, conduct on-site temperature and deformation monitoring, and determine the degradation depth range and degree of permafrost strata; Step S02, determining the target temperature of permafrost protection at the diseased work site in combination with the structural characteristics of the permafrost layer, the moisture content and the stability type of the permafrost; Step S03: Based on the heat storage theory, the dynamic time series change value of the cooling load of the permafrost foundation per unit length along the traffic line and the required peak cooling capacity are calculated; Step S04: determining the arrangement spacing of multiple refrigeration devices according to the timeliness requirements of permafrost protection; Step S05, determining the refrigeration capacity of the refrigeration device and the start-up temperature of the cold transport unit according to the peak cooling capacity required for the permafrost foundation per unit length and the longitudinal spacing of the refrigeration device; Step S06: Design, select and prepare the refrigeration device according to its refrigeration capacity; Step S07: On-site installation of the refrigeration device; Step S08: Dynamic operation control of the refrigeration device.

[0015] Further, in step S08, according to the target temperature of permafrost protection determined in step S02, an upper threshold and a lower threshold are pre-set in the PLC controller, which are the permafrost protection target temperature value +1°C and -2°C, respectively. According to the monitoring value of the temperature sensor, the refrigeration device is dynamically controlled.

[0016] Compared with the prior art, the present invention has the following technical advances: (1) The present invention introduces green refrigeration technology from the field of building environment to the field of transportation infrastructure. The refrigeration device adopts a cabinet type with innovative design. The cold energy transfer unit is used for secondary transmission of cold energy. The condensing section and refrigeration section of the refrigeration device and the cold energy transfer unit can be arranged separately according to the application scenario, thereby playing the role of protecting permafrost and having strong adaptability to scenarios.

[0017] (2) The refrigeration device in the present invention uses solar energy as a driving source and is mainly used in the permafrost area of ​​the Qinghai-Tibet Plateau. The Qinghai-Tibet Plateau is rich in solar energy resources. The refrigeration device does not require external power supply and is self-driven, which is green and energy-saving.

[0018] (3) The refrigeration device in the present invention has a high degree of intelligence and can dynamically adjust the device operation mode through a PLC controller according to the actual degree of permafrost degradation, thereby achieving good energy saving performance.

[0019] (4) The refrigeration device of the present invention has no mechanical moving parts and has a long service life. At the same time, the refrigeration device is easy to install, can be operated automatically without human supervision, and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] In the attached picture: Figure 1 It is a schematic diagram of the structure of an absorption refrigeration unit in a refrigeration device according to an embodiment of the present invention; Figure 2This is a schematic diagram of the structure of a solar drive unit in a refrigeration device according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of a cooling capacity transmission unit in a refrigeration device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the installation of a three-layer support plate inside a cabinet in an embodiment of the present invention; Figure 5 This is a schematic diagram of the installation of photovoltaic components on the side of a cabinet in an embodiment of the present invention; Figure 6 Schematic diagram of the structural arrangement of the top of the upper support plate in the cabinet in an embodiment of the present invention; Figure 7 It is a schematic diagram of the structural arrangement of the top of the middle tray in the cabinet and the separated heat pipe in an embodiment of the present invention; Figure 8 Schematic diagram of the structural arrangement of the top of the lower tray in the cabinet in an embodiment of the present invention; Fig. 9 It is a schematic diagram of a plurality of refrigeration devices applied to a roadbed scene in a permafrost region according to an embodiment of the present invention; In the figure: 1-bubble generator, 1001-generator main inlet, 1002-generator secondary inlet; 2-refrigerant; 3-bubble pump; 4-gas-liquid separator; 5-condenser, 5001-condenser main outlet, 5002-condenser secondary outlet; 6-throttle; 7-evaporator, 7001-evaporator main outlet, 7002-evaporator secondary outlet; 8-cold storage assembly; 9-absorber, 9001-absorber main inlet, 9002-absorber secondary inlet, 9003-absorber main outlet, 9004-absorber secondary outlet; 10-liquid reservoir, 10001-liquid reservoir main inlet, 10002-liquid reservoir secondary inlet; 11-main connecting pipe; 12-auxiliary connecting pipe, 120001-first connecting pipe, 120002-second connecting pipe, 120003-third connecting pipe; 13-solar photovoltaic module; 14-power storage module; 15-electric heating module; 16-high temperature flame retardant insulation sleeve; 17-power communication line; 18-PLC remote PLC controller; 19-separated heat pipe, 19001-refrigeration section, 19002-insulation connection section, 19003-condensation section; 20-cabinet, 20001-upper tray, 20002-middle tray, 20003-lower tray, 20004-round hole, 20005-shield, 20006-base; 21-exhaust fan; 22-permafrost layer; 23-temperature sensor. DETAILED DESCRIPTION

[0022] The following specific embodiments may 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 in conjunction with the accompanying drawings.

[0023] like Figure 1 and Fig. 9 As shown, a solar refrigeration device includes a solar drive unit, an absorption refrigeration unit and a cold transmission unit. The absorption refrigeration unit includes a cold storage component 8 and a bubble generator 1, a bubble pump 3, a gas-liquid separator 4, a condenser 5, a throttle 6, an evaporator 7, an absorber 9 and a liquid storage tank 10 which are connected in sequence and filled with a refrigerant 2. The liquid storage tank 10 is connected to the bubble generator 1 through a main connecting pipe 11 to form a closed circulation loop, which serves as the main circulation flow channel of the refrigerant. The cold storage component 8 is used to store the cold generated by the evaporator 7; the electric heating component 15 of the solar drive unit is arranged on the outer wall of the bubble generator 1 to provide a heat source for the volatilization of the refrigerant; the condensing section 19003 of the cold transmission unit is arranged in the cold storage component 8, and the refrigeration section 19001 of the cold transmission unit can be placed in a degraded permafrost layer 22. Among them, the components of the refrigerant 2 include a refrigerant, an absorbent and a diffuser, and the heating temperature of the electric heating component is between the boiling point temperatures of the refrigerant and the absorbent. The refrigerant is heated and volatilized into a gas-liquid mixture in the bubble generator 1. After the flow rate is increased by the bubble pump 3, it enters the gas-liquid separator 4 to separate the absorbent and the refrigerant in the refrigerant 2. The refrigerant in the gaseous refrigerant is liquefied through the condenser 5 and then enters the evaporator 7 after the pressure is reduced and the speed is adjusted by the throttle 6. The refrigerant fully absorbs heat in the evaporator 7 to vaporize the liquid refrigerant, generating a refrigeration effect and storing it in the cold storage component 8. The cooling capacity transmission unit transmits it to the degraded permafrost layer 22; at the same time, the absorber 9 absorbs the refrigerant from the evaporator 7 and refluxes it to the liquid storage tank 10. The liquid storage tank 10 collects the unvaporized liquid refrigerant in the evaporator 7 and adjusts the circulation flow of the refrigerant, and then circulates it to the bubble generator 1 through the main connecting pipe 11.

[0024] In the specific design, the mass ratio of the refrigerant to the absorbent is 1:1 to 1:3, the refrigerant and the absorbent are low-boiling point and high-boiling point media respectively, and the two are miscible; the refrigerant is ammonia, the absorbent is distilled water, the diffuser is inert gas helium, and the filling pressure of the helium is 18 bar.

[0025] The above scheme is further optimized, and further includes auxiliary connecting pipes, which include a first connecting pipe 120001, a second connecting pipe 120002 and a third connecting pipe 120003. The absorber 9 is connected to the generator secondary inlet 1002 through the first connecting pipe 120001 to prevent the internal liquid level of the absorber 9 from being too high, causing the refrigerant to flow in reverse; the condenser 5 is connected to the absorber secondary inlet 9004 through the second connecting pipe 120002, so that the liquid absorbent that is not completely separated in the gas-liquid separator 4 enters the absorber 9; the evaporator 7 is connected to the liquid storage tank secondary inlet 10002 through the third connecting pipe 120003, so that the refrigerant that is not completely vaporized in the evaporator 7 flows into the liquid storage tank 10; the auxiliary connecting pipes serve as auxiliary circulation channels for the refrigerant. Figure 1 As shown, the specific connection relationship of the absorption refrigeration unit is as follows: The bubble generator 1 includes 1 outlet and 2 inlets, and the 2 inlets are respectively a main inlet 1001 of the generator and a secondary inlet 1002 of the generator; the bubble generator 1 is filled with refrigerant 2, the outlet of the bubble generator 1 is connected to the inlet of the bubble pump 3, the outlet of the bubble pump 3 is connected to the inlet of the gas-liquid separator 4, and the outlet of the gas-liquid separator 4 is connected to the inlet of the condenser 5; the condenser 5 includes 1 inlet and 2 outlets, and the 2 outlets are respectively a main outlet 5001 of the condenser and a secondary outlet 5002 of the condenser, and the secondary outlet 5002 of the condenser is located at the beginning of the condenser, the main outlet 5001 of the condenser is connected to the inlet of the throttle 6, and the outlet of the throttle 6 is connected to the inlet of the evaporator 7; the evaporator 7 includes 1 inlet and 2 outlets, and the 2 outlets They are respectively an evaporator main outlet 7001 and an evaporator secondary outlet 7002. The evaporator 7 is located in the cold storage assembly 8, and the evaporator main outlet 7001 is connected to the absorber 9; the absorber 9 includes 2 inlets and 2 outlets, which are respectively an absorber main inlet 9001, an absorber secondary inlet 9002, an absorber main outlet 9003, and an absorber secondary outlet 9004, and the evaporator main outlet 7001 is connected to the absorber main inlet 9001; the liquid reservoir 10 includes 1 outlet and 2 inlets, the 2 inlets are respectively a liquid reservoir main inlet 10001 and a liquid reservoir secondary inlet 10002, the absorber main outlet 9003 is connected to the liquid reservoir main inlet 10001, and the outlet of the liquid reservoir 10 is connected to the generator main inlet 1001. At this point, the outlet of the bubble generator 10, the inlet and outlet of the bubble pump 3, the inlet and outlet of the gas-liquid separator 4, the inlet of the condenser 5 and the condenser main outlet 5001, the inlet and outlet of the throttle 6, the inlet of the evaporator 7 and the evaporator main outlet 7001, the absorber main inlet 9001 and the absorber main outlet 9003, the liquid reservoir main inlet 10001 and the outlet of the liquid reservoir 10, and the generator main inlet and outlet 1001 are connected in sequence using the main connecting pipe 11 to form a closed circulation loop, which serves as the main circulation flow channel of the refrigerant 2.

[0026] At the same time, auxiliary connecting pipes are used to connect the bubble generator 1 and the absorber 9, the condenser 5 and the absorber 9, and the evaporator 7 and the liquid storage 10, respectively, to assist the circulation of the refrigerant 2. Specifically: (1) The generator secondary inlet 1002 and the absorber secondary outlet 9004 are connected through the first connecting pipe 120001. The function of the first connecting pipe 120001 is that when there is a pressure difference between the generator 1 and the absorber 9, causing the refrigerant 2 to flow in reverse and the liquid level inside the absorber 9 is too high, the refrigerant 2 can flow into the generator through the branch first connecting pipe 120001 to prevent the liquid level inside the absorber 9 from being too high. (2) The condenser secondary outlet 5002 is connected to the absorber secondary inlet 9002 through the second connecting pipe 120002. The function of the second connecting pipe 120002 is to allow the liquid absorbent 20002 that is not completely separated in the gas-liquid separator 4 to enter the absorber 9 through the branch 11002, further purify the refrigerant 20001 that is about to enter the throttle 6, prevent the throttle 6 from ice blockage, and ensure the refrigeration effect of the evaporator 7. (3) The evaporator secondary outlet 7002 is connected to the liquid storage secondary inlet 10002 through the third connecting pipe 120003. The function of the third connecting pipe 120003 is to allow the refrigerant 20001 that is not completely vaporized in the evaporator 7 to flow into the liquid storage through the branch third connecting pipe 120003.

[0027] The specific production of each component in the absorption refrigeration unit is as follows: The bubble generator 1 adopts a stainless steel cubic container, and its function is to volatilize the refrigerant 2 into a gas-liquid mixture by heating. The core component of the bubble pump 3 is a gradually contracting and expanding variable-section stainless steel pipe, which has the beneficial effect of increasing the flow rate of the refrigerant without external power drive. The function of the bubble pump 3 is to lift and move the gas-liquid mixed refrigerant 2 generated by the bubble generator 1 upward.

[0028] The gas-liquid separator 4 is a stainless steel container with a multi-cavity serpentine channel inside. Its beneficial effect is that it relies on the gravity difference between the gaseous and liquid refrigerants to allow the gaseous refrigerant to pass through while the liquid refrigerant is deposited. The function of the gas-liquid separator 4 is to separate the absorbent and the refrigerant in the refrigerant 2 by changing the flow direction of the refrigerant 2 and the heat exchange area with the air environment, so that the absorbent is cooled and liquefied and then flows back to the bubble generator 1. The condenser 5 is a stainless steel solenoid with a heat dissipation fin welded on the outer wall. The function of the condenser 5 is to release heat and liquefy the refrigerant in the gaseous refrigerant 2.

[0029] The core component of the throttle 6 is a spiral small-diameter stainless steel tube, which has the beneficial effect of reducing the flow pressure of the refrigerant 2 and automatically adjusting the flow rate of the refrigerant 2 according to the pressure difference between the inlet and outlet of the throttle 6; the function of the throttle 6 is to reduce the pressure of the liquid refrigerant from the condenser 5.

[0030] The core component of the evaporator 7 is three built-in series-connected extended-range disc evaporation ends, which have the beneficial effect of increasing the flow length of the refrigerant 2 in a low-pressure environment to fully absorb heat and vaporize. The function of the evaporator 7 is to vaporize the liquid refrigerant and absorb heat to produce a refrigeration effect.

[0031] The cold storage component 8 is a phase change energy storage material package, which is used to store the cold energy generated by the evaporator 7. The absorber 9 is an elliptical stainless steel tank, the upper layer of the absorber 9 is a gaseous refrigerant, and the lower layer is a dilute solution composed of a liquid refrigerant and an absorbent, which is used to absorb the gaseous refrigerant from the evaporator 7.

[0032] The liquid storage device 10 is a cylindrical stainless steel tank. The function of the liquid storage device 10 is to dynamically and flexibly adjust the refrigerant circulation flow rate according to the operating state of the absorption refrigeration unit and collect the unvaporized liquid refrigerant 2 in the evaporator 7.

[0033] The stainless steel pipe components used in making the above absorption refrigeration unit are made of 304 stainless steel, which has the advantages of good processing performance, high toughness and corrosion resistance.

[0034] The working principle of the above absorption refrigeration unit is as follows: the refrigerant in the refrigerant 2 is a low boiling point medium, the absorbent is a high boiling point medium, the refrigerant dissolves in the absorbent and the absorption ratio of the absorbent to the refrigerant decreases as the temperature increases. The diffusion agent fills the inside of the closed loop of the absorption refrigeration unit, and its function is to maintain a suitable low pressure range in the evaporator 7, which is conducive to the evaporation and diffusion of the refrigerant. The refrigeration process is: Step 1: The bubble generator 1 contains a mixed solution of refrigerant and absorbent. The PLC controller 18 controls the electric heating component 15 to start and heat the bubble generator 1. As the temperature rises, the refrigerant in the mixed solution continuously desorbs from the absorbent and evaporates into gas, becoming a low-density, high-temperature, and high-pressure refrigerant vapor. At the same time, the remaining solution in the bubble generator 1 returns to the absorber 9 and gradually cools down.

[0035] Step 2: The gaseous refrigerant and the gas-liquid mixture of the liquid absorbent generated by the bubble generator 1 enter the bubble pump 3 under the action of the diffuser, and the gas-liquid mixture moves upward to the gas-liquid separator 4 under the lifting action of the bubble pump 3, and the liquid absorbent in the gas-liquid mixture flows downward under the action of gravity and returns to the bubble generator 1. At the same time, if there is any residual liquid absorbent, it will flow into the absorber 9 through the second connecting pipe 120002. The gaseous refrigerant continues to enter the condenser 5, and after heat dissipation, it is condensed into a low-temperature and low-pressure liquid refrigerant.

[0036] Step 3: The liquid refrigerant flows into the throttle 6 under the action of gravity, and becomes a gas-liquid mixture under the pressure reduction effect of the throttle 6, and then enters the evaporator 7, where it continues to be depressurized to the evaporation pressure and then vaporizes. The vaporization process absorbs external heat, produces a refrigeration effect, and becomes a low-temperature and low-pressure gaseous refrigerant. At the same time, the residual liquid refrigerant that has not been completely vaporized will flow into the liquid storage 10 through the third connecting pipe 120003.

[0037] Step 4: The gaseous refrigerant enters the absorber 9 and is absorbed by the absorbent in the absorber 9 to become a mixed solution, and the concentration of the refrigerant in the mixed solution gradually increases, and the mixed solution flows into the liquid storage tank 10 under the action of gravity. At the same time, if the liquid level inside the absorber 9 is too high, the mixed solution flows into the bubble generator 1 through the first connecting pipe 120001.

[0038] Step 5: The mixed solution in the liquid storage tank 10 continues to flow back into the bubble generator 1 and enters the next refrigeration cycle. Thus, the refrigerant undergoes a gas-liquid cycle through the circulation separation and absorption of the refrigerant, and the refrigeration effect is generated through the refrigerant gasification and heat absorption in the evaporator 4.

[0039] In a specific embodiment of the present invention, Figure 3 As shown, the cold transport unit is a separate heat pipe 19, which includes a condensing section 1901, an insulating connecting section 1902 and a refrigeration section 1903. The insulating connecting section 1902 is arranged between the condensing section 1901 and the refrigeration section 1903. The insulating connecting section 1902 is a flexible pipe. The condensing section 1901 and the refrigeration section 1903 are both rigid pipes. The condensing section 1901 is located in the cold storage component 8 of the absorption refrigeration unit, and the refrigeration section 1903 can be inserted into the degraded permafrost layer 22, and its size matches the protection depth of the permafrost layer 22; the interior of the separate heat pipe 19 is filled with a heat transfer medium (heat medium), and the starting temperature of the separate heat pipe 19 (i.e., the boiling point temperature of the heat transfer medium) is lower than the target temperature of permafrost protection. When the temperature of the outer wall of the evaporator 7 is lower than the condensation temperature corresponding to the heat medium in the condensation section of the separate heat pipe, the cold transmission unit starts to operate, the heat medium absorbs cold and liquefies, the liquid heat medium flows to the refrigeration section under the action of gravity due to the increase in density, the liquid heat medium will exchange heat with the surrounding permafrost layer in the refrigeration section, and the heat medium will gasify after outputting cold, and the gaseous heat medium will rise and flow back to the condensation section due to the decrease in density, thus circulating back and forth, continuously transmitting cold to the lower permafrost layer 22. Among them, the condensation section and the refrigeration section are both stainless steel pipes, and the thermal insulation connection section is a flexible stainless steel bellows.

[0040] As a preferred structure, Figure 2As shown, the solar drive unit includes a photovoltaic component 13, a power storage component 14, an electric heating component 15 and a PLC controller 18. The photovoltaic component 13, the power storage component 14, the PLC controller 18 and the electric heating component 15 communication lines are connected in sequence. The photovoltaic component 13 is used to convert sunlight into electrical energy during the day, and the power storage component 14 is used to store the electrical energy generated by the photovoltaic component 13. The power storage component 14 is connected to the electric heating component 5 to provide power for the electric heating component 15 to ensure the continuity of power supply day and night; the PLC controller 18 can remotely control the overcharge and overdischarge of the power storage component 14 and the start and stop of the electric heating component 15. At the same time, the electric heating component 15 is coated with a high-temperature flame-retardant insulation cover 16, which is used to prevent heat loss and prevent high temperature from affecting the operating status of other components. During production, the electric heating component 15 is a carbon fiber heating cable, and the high-temperature flame-retardant insulation cover 16 is made of rock wool.

[0041] When assembling, Figure 4 , 5 As shown, the absorption refrigeration unit, the power storage component 14, the electric heating component 15 and the PLC controller 18 are all arranged in the cabinet 20, the photovoltaic component 13 is arranged outside the cabinet 20, the inner side of the cabinet door of the cabinet 20 is provided with a shield 2005, and the PLC controller 18 is arranged on the shield 2005; the interior of the cabinet 20 is provided with an upper tray 20001, a middle tray 20002 and a lower tray 20003 from top to bottom, and the gas-liquid separator 4 and the condenser 5 are arranged on the upper tray 20001 (as shown in FIG. Figure 6 As shown), the throttle 6, evaporator 7 and cold storage assembly 8 are arranged on the middle support plate 20002 (as shown Figure 7 As shown), the bubble generator 1, the bubble pump 3, the absorber 9, the liquid storage tank 10 and the power storage assembly 14 are arranged on the lower support plate 20003 (as shown Figure 8 As shown); an exhaust fan 21 is provided on the inner wall above the upper tray 20001, and the exhaust fan 21 is connected to the PLC controller 18 to exhaust the heat emitted by the condenser 5; the exhaust fan 21 is connected in parallel with the electric heating component 15 and the power storage component 14; the upper tray 20001, the middle tray 20002 and the lower tray 20003 are all provided with through holes 2004, which are used to penetrate the auxiliary connecting pipe and the main connecting pipe 11 of the inlet and outlet of the liquid storage tank 10, and the main connecting pipe 11 and the auxiliary connecting pipe are connected to each component through the circular holes 20004 pre-drilled on each tray. The cabinet 20 is specifically installed as follows: (1) An exhaust fan 20 is installed on the inner wall of the cabinet 20 above the upper tray 20001. The function of the upper tray 20001 is to isolate the condenser 5 in a separate environment and quickly discharge the heat emitted by the condenser 5 out of the cabinet through the exhaust fan 21 to prevent affecting the cooling effect of the evaporator 7; (2) The function of the middle tray 20002 is to isolate the power storage component 14 and the electric heating component 15 in a separate environment to prevent affecting the cooling effect of the evaporator 7; (3) The PLC controller 18 is installed on the shield 20005; (4) The photovoltaic component 13 is installed on the outer wall of the cabinet 20 to facilitate exposure to sunlight.

[0042] In a specific embodiment of the present invention, the PLC controller is embedded with two thresholds and two commands. The two thresholds are the upper and lower thresholds of the permafrost layer temperature. The two commands are respectively the first-class command and the second-class command. The first-class command: controls the electric heating component and the exhaust fan to be powered on and run; the second-class command: controls the electric heating component and the exhaust fan to be powered off and stopped. The execution basis of the two commands is as follows: When the monitoring value of the temperature sensor buried in the permafrost layer is higher than the upper limit threshold, the first type of command is executed; when the monitoring value of the temperature sensor buried in the permafrost layer is lower than the lower limit threshold, the second type of command is executed.

[0043] like Fig. 9 As shown, the present invention is applied to the permafrost foundation scene under the roadbed in the permafrost area. The cabinets 20 are evenly arranged on both sides of the melting groove along the roadbed direction and fixed on the cabinet base 20006 at the foot of the roadbed slope. The permafrost refrigeration section 19001 is buried in the permafrost layer 22, and the temperature sensor 23 is buried in the middle position of the adjacent cabinet 20. The temperature sensor 23 covers the permafrost degradation depth range. During the day with solar radiation, the photovoltaic component 13 generates electricity and charges the power storage component 14. When the temperature sensor 23 detects that the temperature of the permafrost layer 22 rises to the preset control lower limit threshold, the PLC controller 18 executes the first type of command, and the solar refrigeration device starts to operate refrigeration. Since the power storage component 14 stores a certain amount of electrical energy, the solar refrigeration device can maintain continuous operation even at night and on cloudy days without solar radiation. Until the temperature sensor 23 detects that the temperature of the permafrost layer 22 drops to the preset lower limit threshold, the PLC controller 18 executes the second type of command, and the solar refrigeration device stops and enters the standby state.

[0044] The present invention also provides a permafrost protection method, which uses the above-mentioned solar refrigeration device for refrigeration, comprising the following steps: Step S01: Select a permafrost degradation site scenario for transportation infrastructure, conduct on-site temperature and deformation monitoring, and determine the degradation depth range and degree of permafrost strata; First, select the transportation infrastructure construction sites where permafrost diseases occur, drill temperature monitoring holes and deformation monitoring holes at the diseased sites to conduct field tests, and determine the temperature change curve, upper limit depth, temperature amplitude and annual average temperature of the permafrost layer; secondly, collect soil samples for indoor testing to determine the structural characteristics and moisture content (ice content) of the permafrost. Then, according to the provisions of the "Design Code for Building Foundations in Frozen Areas" (JGJ 118-2011) on the temperature threshold corresponding to the stability type of permafrost, locate the depth range and degree of degradation of permafrost where temperature rise and degradation occur. The above specific implementation processes are all existing technologies and will not be repeated here.

[0045] Step S02, determining the target temperature of permafrost protection at the diseased work site in combination with the structural characteristics of the permafrost layer, the moisture content and the stability type of the permafrost; First, the temperature coefficients were assigned according to the different ranges of the three elements of the structural characteristics, moisture content and stability type of the permafrost layer. The assignment scheme is as follows: 1) In terms of the element of “structural characteristics of permafrost layers”, the temperature coefficients of the overall structure, network structure, and layered structure are 1.10, 1.30, and 1.60, respectively.

[0046] 2) In terms of the "water content" factor, the temperature coefficients of the less ice, more ice, rich ice, saturated ice, and ice containing soil are 1.05, 1.10, 1.15, 1.30, and 1.50, respectively.

[0047] 3) In terms of the “permafrost stability type” factor, the temperature coefficients of the extremely stable, stable, metastable, transitional, and unstable types are 1.05, 1.10, 1.15, 1.25, and 1.45, respectively.

[0048] Secondly, according to the structural characteristics of the permafrost layer, the moisture content and the permafrost stability type of the specific diseased work site determined in step S01, that is, the actual conditions of the three elements, the corresponding temperature coefficient values ​​are determined respectively.

[0049] Then, according to the annual average temperature of the permafrost layer determined in step S01, the annual average temperature is multiplied by the temperature coefficient values ​​of the three elements in sequence to obtain the permafrost protection target temperature.

[0050] Step S03: Based on the heat storage theory, the dynamic time series change value of the cooling load of the permafrost foundation per unit length along the traffic line and the required peak cooling capacity are calculated; First, according to the temperature change curve of the permafrost layer obtained by the test in step S01, based on the heat storage theory, the permafrost protection target temperature determined in step S02 is used as a benchmark, and the calculation step length is per hour to calculate the dynamic time series change law of the cooling load of the permafrost foundation along the unit length of the traffic line and within the influence range of the line stability. Then, with a daily calculation step length, the peak cooling capacity and average cooling capacity corresponding to the warm season are compared and determined. The above specific calculation processes are all existing technologies and will not be repeated here.

[0051] Step S04: determining the arrangement spacing of multiple refrigeration devices according to the timeliness requirements of permafrost protection; According to the type and severity of the damage to the transportation infrastructure caused by permafrost degradation, the timeliness requirements of permafrost protection are judged. If the timeliness requirements are strict and the thermal stability of the permafrost foundation needs to be quickly restored in a short period of time, the longitudinal spacing of the solar refrigeration devices along the transportation lines shall be 1.0 to 2.0 m; if the timeliness requirements are low, the longitudinal spacing of the solar refrigeration devices along the transportation lines shall be 2.0 to 4.0 m.

[0052] Step S05, determining the refrigeration capacity of the refrigeration device and the start-up temperature of the cold transport unit according to the peak cooling capacity required for the permafrost foundation per unit length and the longitudinal spacing of the refrigeration device; The refrigeration capacity of a single absorption refrigeration device is obtained by multiplying the longitudinal spacing of the solar refrigeration device determined in step S04 and the peak cooling capacity required per unit length of the permafrost foundation determined in step S03.

[0053] Step S06: Design, select and prepare the refrigeration device according to its refrigeration capacity; According to the refrigeration capacity of a single absorption refrigeration device determined in step S05, the main components of the absorption refrigeration unit and the solar drive unit are designed and selected. First, the height of the permafrost refrigeration section of the cold transfer unit is taken as the permafrost foundation degradation depth value determined in step S01; then, according to the on-site equipment installation conditions, the installation position of the absorption refrigeration device cabinet is determined. The principle is to be close to the junction of structures such as the roadbed slope foot and the permafrost foundation, and then the size of the insulated connection section of the cold transfer unit is determined. After that, according to the target temperature of permafrost protection determined in step S02, the start-up temperature of the separate heat pipe is determined. The start-up temperature should be lower than the target temperature of permafrost protection by more than 2°C. The purpose is to maintain a sufficient temperature gradient between the output temperature of the separate heat pipe refrigeration section and the permafrost to ensure the cold diffusion effect. Finally, according to the component selection design plan, a refrigeration device is prepared.

[0054] Step S07: On-site installation of the refrigeration device; The on-site installation of the solar cooling device was carried out at the end of the warm season and the beginning of the cold season to minimize the negative thermal disturbance to the permafrost during the construction process. First, the permafrost cooling section and temperature sensor of the cold transmission unit were drilled through the borehole; then, the cabinet of the solar cooling device was installed; then, the permafrost cooling section and the condensing section inside the cabinet were connected by an adiabatic connection section; finally, the PLC controller and the temperature sensor were connected, and the device was debugged to normal operation and entered the standby state.

[0055] Step S08: Dynamic operation control of the refrigeration device.

[0056] According to the permafrost protection target temperature determined in step S02, the upper and lower thresholds are pre-set in the PLC controller, which are the permafrost protection target temperature value +1°C and -2°C, respectively. The purpose of taking the upper threshold as the permafrost protection target temperature value +1°C is to effectively control the permafrost degradation process and avoid the frequent start and stop of the solar refrigeration device near the critical degradation state of the permafrost, which affects the equipment life. The purpose of taking the lower threshold as the permafrost protection target temperature value -2°C is to ensure that the degraded permafrost can store enough cold capacity under the action of the solar refrigeration device to improve the anti-degradation potential, and to avoid the waste of cold capacity caused by excessive protection, thereby improving the equipment life.

[0057] The refrigeration device is dynamically controlled according to the monitoring value of the temperature sensor.

[0058] In summary, the present invention has the advantages of reasonable design and good refrigeration effect. The absorption refrigeration unit and the solar drive unit are integrated on the cabinet for easy installation. The separate heat pipe has strong scene adaptability and can be intelligently controlled according to the permafrost temperature through remote control of the PLC controller. The present invention is applicable to the field of thermal stability maintenance of foundations in permafrost areas and prevention and control of frozen soil degradation. It can effectively prevent and control frozen soil degradation, self-drive operation, and green energy saving.

[0059] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is 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 can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A solar refrigeration device, characterized in that: The refrigeration device includes a solar drive unit, an absorption refrigeration unit and a cold energy transfer unit. The absorption refrigeration unit includes a cold storage component and a bubble generator, a bubble pump, a gas-liquid separator, a condenser, a throttle, an evaporator, an absorber and a liquid storage tank which are connected in sequence and filled with refrigerant. The liquid storage tank is connected to the bubble generator to form a closed circulation loop, which serves as the main circulation flow channel of the refrigerant. The cold storage component is used to store the cold energy generated by the evaporator; the electric heating component of the solar drive unit is arranged on the outer wall of the bubble generator to provide a heat source for the volatilization of the refrigerant; the condensing section of the cold energy transfer unit is arranged in the cold storage component, and the refrigeration section of the cold energy transfer unit can be placed in a degraded permafrost layer.

2. A solar refrigeration device according to claim 1, characterized in that: The components of the refrigerant include a refrigerant, an absorbent and a diffuser, the mass ratio of the refrigerant to the absorbent is 1:1 to 1:3, and the diffuser is an inert gas; the heating temperature of the electric heating component is between the boiling points of the refrigerant and the absorbent.

3. A solar refrigeration device according to claim 2, characterized in that: The refrigerant of the refrigerant is ammonia, the absorbent is distilled water, the diffusant is helium, and the filling pressure of the helium is 18 bar.

4. A solar refrigeration device according to claim 1, characterized in that: The cold energy transfer unit is a separate heat pipe, which includes a condensing section, an insulating connecting section and a refrigeration section. The insulating connecting section is arranged between the condensing section and the refrigeration section. The insulating connecting section is a flexible pipe. The condensing section and the refrigeration section are both rigid pipes. The size of the refrigeration section matches the protection depth of the permafrost layer. The interior of the separate heat pipe is filled with a heat transfer medium, and the boiling point temperature of the heat transfer medium is lower than the target temperature of permafrost protection.

5. A solar refrigeration device according to any one of claims 1 to 4, characterized in that: It also includes an auxiliary connecting pipe, which includes a first connecting pipe, a second connecting pipe and a third connecting pipe. The absorber is connected to the secondary inlet of the generator through the first connecting pipe to prevent the refrigerant from flowing in reverse due to the excessive liquid level inside the absorber. The condenser is connected to the secondary inlet of the absorber through the second connecting pipe to allow the liquid absorbent that is not completely separated in the gas-liquid separator to enter the absorber. The evaporator is connected to the secondary inlet of the liquid storage tank through the third connecting pipe, so that the refrigerant that is not completely vaporized in the evaporator flows into the liquid storage tank.

6. A solar refrigeration device according to claim 5, characterized in that: The solar drive unit includes a photovoltaic component, a power storage component, an electric heating component and a PLC controller. The photovoltaic component, the power storage component, the PLC controller and the electric heating component communication lines are connected in sequence. The photovoltaic component is used to convert solar energy into electrical energy. The power storage component is used to store the electrical energy generated by the photovoltaic component. The power storage component is connected to the electric heating component to provide power for the electric heating component; the PLC controller is used to control the overcharging and overdischarging of the power storage component and the start and stop of the electric heating component.

7. A solar refrigeration device according to claim 6, characterized in that: The absorption refrigeration unit, power storage component, electric heating component and PLC controller are all arranged in the cabinet, the photovoltaic component is arranged on the outside of the cabinet, a shield is provided on the inner side of the cabinet door of the cabinet, and the PLC controller is arranged on the shield; the interior of the cabinet is provided with an upper tray, a middle tray and a lower tray from top to bottom, the gas-liquid separator and condenser are arranged on the upper tray, the throttle, evaporator and cold storage component are arranged on the middle tray, the bubble generator, bubble pump, absorber, liquid storage tank and power storage component are arranged on the lower tray; an exhaust fan is provided on the inner wall above the upper tray, and the exhaust fan is connected to the PLC controller; the exhaust fan is connected to the electric heating component in parallel with the power storage component; through holes are provided on the upper tray, the middle tray and the lower tray for passing through the auxiliary connecting pipe and the main connecting pipe of the liquid storage tank inlet and outlet.

8. A solar refrigeration device according to claim 6, characterized in that: The PLC controller has two built-in thresholds and two commands. The two thresholds are the upper and lower thresholds of the permafrost layer temperature. The two commands are the first-class command and the second-class command. The first-class command controls the electric heating component and the exhaust fan to be powered on and operated. The second-class command controls the electric heating component and the exhaust fan to be powered off and stopped. The execution basis of the two commands is as follows: When the monitoring value of the temperature sensor buried in the permafrost layer is higher than the upper limit threshold, the first type of command is executed; when the monitoring value of the temperature sensor buried in the permafrost layer is lower than the lower limit threshold, the second type of command is executed.

9. A method for protecting permafrost, characterized in that: The solar refrigeration device according to claim 8 comprises the following steps: Step S01: Select a permafrost degradation site scenario for transportation infrastructure, conduct on-site temperature and deformation monitoring, and determine the degradation depth range and degree of permafrost strata; Step S02, determining the target temperature of permafrost protection at the diseased work site in combination with the structural characteristics of the permafrost layer, the moisture content and the stability type of the permafrost; Step S03: Based on the heat storage theory, the dynamic time series change value of the cooling load of the permafrost foundation per unit length along the traffic line and the required peak cooling capacity are calculated; Step S04: determining the arrangement spacing of multiple refrigeration devices according to the timeliness requirements of permafrost protection; Step S05, determining the refrigeration capacity of the refrigeration device and the start-up temperature of the cold transport unit according to the peak cooling capacity required for the permafrost foundation per unit length and the longitudinal spacing of the refrigeration device; Step S06: Design, select and prepare the refrigeration device according to its refrigeration capacity; Step S07: On-site installation of the refrigeration device; Step S08: Dynamic operation control of the refrigeration device.

10. The permafrost protection method according to claim 9, characterized in that: In step S07, according to the target temperature of permafrost protection determined in step S02, the upper and lower thresholds are pre-set in the PLC controller, which are the permafrost protection target temperature values ​​of +1°C and -2°C, respectively. The refrigeration device is dynamically controlled according to the monitoring value of the temperature sensor.

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