A cooling system for a tunneling machine and a control method thereof

Abstract

This invention provides a cooling system and control method for a tunnel boring machine (TBM), comprising a refrigeration unit and a recovery unit. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, and a second evaporator connected in sequence. The second evaporator is used to cool fresh air, which in turn cools the cutterhead and forms return air. A cooling water pump is connected to the shell-and-tube condenser and supplies refrigerant to it. A chilled water pump is connected to the first evaporator and is connected to the motor and the recovery unit via a six-way valve. The chilled water pump provides a cooling medium to the motor to cool it. The six-way valve adjusts the connection status between the chilled water pump, the motor, and the recovery unit based on the return air temperature. This invention can simultaneously meet the cooling requirements of both the TBM's motor and cutterhead.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring machine (TBM) cooling technology, and in particular to a TBM cooling system, a TBM, and a TBM cooling system control method. Background Technology

[0002] During operation, the internal motors of a tunnel boring machine (TBM) need cooling, as does the cutterhead at the head of the TBM. The traditional cooling method involves using two chillers on the TBM: one supplies cooling water to the motors and the other supplies cooling air to the cutterhead. However, the two cooling systems on the same TBM are not highly integrated, making overall control inconvenient. Summary of the Invention

[0003] In view of the above problems, embodiments of the present invention are proposed to provide a tunnel boring machine cooling system, a tunnel boring machine, and a tunnel boring machine cooling system control method to overcome or at least partially solve the above problems.

[0004] To address the aforementioned problems, in a first aspect of the present invention, an embodiment of the present invention discloses a tunnel boring machine (TBM) cooling system. The TBM includes a motor and a cutterhead, and the TBM cooling system includes a refrigeration unit and a recycling combination cabinet.

[0005] The refrigeration unit includes a compressor, an oil separator, a shell and tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump;

[0006] The compressor, the oil separator, the shell and tube condenser, the first expansion valve, the first evaporator, the second expansion valve, and the second evaporator are connected in sequence to form a cooling circulation loop; the second evaporator is used to cool the fresh air, and the cooled fresh air is used to cool the blade disc and form return air; the cooling water pump is connected to the shell and tube condenser and is used to deliver refrigerant to the shell and tube condenser;

[0007] The chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recycling cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool the motor; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recycling cabinet based on the temperature of the return air.

[0008] Optionally, the six-way valve is used to connect the outlet of the chilled water pump to the inlet of the recycling cabinet when the temperature of the return air is lower than the outlet temperature of the cooling medium of the chilled water pump, the outlet of the recycling cabinet to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump.

[0009] Optionally, the six-way valve is used to connect the outlet of the chilled water pump to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump, when the temperature of the return air is higher than the inlet temperature of the cooling medium of the chilled water pump, thereby shutting off the recovery combination cabinet.

[0010] Optionally, the six-way valve is used to connect the outlet of the motor to the inlet of the recycling cabinet when the temperature of the return air is higher than the outlet temperature of the cooling medium of the chilled water pump and lower than the inlet temperature of the cooling medium of the chilled water pump. The outlet of the recycling cabinet is connected to the inlet of the chilled water pump, and the outlet of the chilled water pump is connected to the inlet of the motor.

[0011] Optionally, the tunnel boring machine cooling system further includes:

[0012] A hydraulic fan exhaust cooling tower is connected to the cooling water pump and the shell-and-tube condenser to cool the refrigerant in the shell-and-tube condenser; the cooling water pump is used to deliver the cooled refrigerant to the shell-and-tube condenser.

[0013] Optionally, the recycling combination cabinet includes:

[0014] A finned heat exchanger is used for heat exchange with the cooling medium.

[0015] A fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation.

[0016] In a second aspect of the present invention, an embodiment of the present invention discloses a tunnel boring machine, comprising: a motor, a cutterhead, and a tunnel boring machine cooling system as described above, wherein the tunnel boring machine cooling system is used to cool the motor and the cutterhead.

[0017] In a third aspect of the invention, an embodiment of the invention discloses a control method for a tunnel boring machine (TBM) cooling system. The TBM includes a motor and a cutterhead. The TBM cooling system comprises a refrigeration unit and a recovery unit; the refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump; the compressor, the oil separator, the shell-and-tube condenser, the first expansion valve, the first evaporator, the second expansion valve, and the second evaporator are sequentially connected to form a cooling cycle. The method includes: a circuit; the second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the blade disc and form return air; the cooling water pump is connected to the shell and tube condenser, and the cooling water pump is used to deliver refrigerant to the shell and tube condenser; the chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recovery combination cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool the motor; the six-way valve is used to adjust the connection status of the chilled water pump with the motor and the recovery combination cabinet based on the temperature of the return air; the method includes:

[0018] The frequency of the chilled water pump is controlled based on the temperature of the cooling medium.

[0019] The operation of the recycling cabinet is controlled based on the temperature of the return air.

[0020] Optionally, the step of controlling the frequency of the chilled water pump based on the temperature of the cooling medium includes:

[0021] Determine whether the temperature of the cooling medium is greater than a first preset temperature threshold;

[0022] When the temperature of the cooling medium is greater than the first preset temperature threshold, the frequency of the chilled water pump is increased.

[0023] When the temperature of the cooling medium is not greater than the first preset temperature threshold, the frequency of the chilled water pump is reduced.

[0024] Optionally, the step of controlling the operation of the recycling cabinet based on the temperature of the return air includes:

[0025] Determine whether the temperature of the return air is greater than a second preset temperature threshold;

[0026] When the temperature of the return air is greater than the second preset temperature threshold, the frequency of the recycling combination cabinet is increased;

[0027] When the temperature of the return air is not greater than the second preset temperature threshold, the frequency of the recycling combination cabinet is reduced.

[0028] The embodiments of the present invention have the following advantages:

[0029] This invention embodiment utilizes a refrigeration unit and a recycling combination cabinet. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the blade disc, forming return air. The cooling water pump is connected to the shell-and-tube condenser and is used to pump water into the shell-and-tube condenser. The system delivers refrigerant; the chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recovery combination cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool it; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recovery combination cabinet based on the temperature of the return air; by producing both cold air and cooling medium through a single refrigeration system, the cooling needs of the tunnel boring machine under two different working conditions are solved, the system complexity is reduced, and the control is more convenient; furthermore, the series arrangement of the two evaporators and the expansion valve, and the use of the recovery combination cabinet, reduce the energy consumption of the refrigeration system. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the layout of an embodiment of a tunnel boring machine cooling system according to the present invention;

[0031] Figure 2 This is a schematic diagram of an embodiment of a tunnel boring machine cooling system according to the present invention;

[0032] Figure 3 This is a flowchart illustrating the steps of an embodiment of the shield tunneling machine cooling system control method of the present invention;

[0033] Figure 4 This is a flowchart illustrating the steps of a shield machine cooling system control method according to the present invention.

[0034] Explanation of reference numerals in the attached drawings: 1-Compressor; 2-Oil separator; 3-Shell and tube condenser; 4-First expansion valve; 5-First evaporator; 6-Second expansion valve; 7-Second evaporator; 8-Chiller water pump; 9-Six-way valve; 10-Recovery combination cabinet; 11-Cooling water pump; 12-Hydraulic fan exhaust air cooling tower; 13-Refrigeration unit. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Reference Figure 1A schematic diagram of the layout of an embodiment of a tunnel boring machine cooling system according to the present invention is shown; refer to Figure 2 The diagram illustrates a schematic representation of an embodiment of a tunnel boring machine (TBM) cooling system according to the present invention. The TBM includes a motor and a cutterhead.

[0037] The tunnel boring machine cooling system may specifically include: a refrigeration unit 13 and a recycling combination cabinet 10;

[0038] The refrigeration unit 13 includes a compressor 1, an oil separator 2, a shell and tube condenser 3, a first expansion valve 4, a first evaporator 5, a second expansion valve 6, a second evaporator 7, a chilled water pump 8, a six-way valve 9, and a cooling water pump 11.

[0039] The compressor 1, the oil separator 2, the shell and tube condenser 3, the first expansion valve 4, the first evaporator 5, the second expansion valve 6, and the second evaporator 7 are connected in sequence to form a cooling circulation loop; the second evaporator 7 is used to cool the fresh air, and the cooled fresh air is used to cool the blade disc and form return air; the cooling water pump 11 is connected to the shell and tube condenser 3, and the cooling water pump 11 is used to deliver refrigerant to the shell and tube condenser 3;

[0040] The chilled water pump 8 is connected to the first evaporator 5, and the chilled water pump 8 is connected to the motor and the recycling combination cabinet 10 through the six-way valve 9; the chilled water pump 8 is used to provide cooling medium to the motor to cool the motor; the six-way valve 9 is used to adjust the connection status of the chilled water pump 8 with the motor and the recycling combination cabinet 10 based on the temperature of the return air.

[0041] In this embodiment of the invention, the refrigeration system comprises a compressor 1, an oil separator 2, a shell-and-tube condenser 3, a first expansion valve 4, a first evaporator 5, a second expansion valve 6, a second evaporator 7, a chilled water pump 8, a six-way valve 9, and a cooling water pump 11. Driven by the compressor 1, the refrigerant first passes through the oil separator 2 to separate the lubricating oil and refrigerant, then enters the shell-and-tube condenser to release heat to the cooling medium. Next, it enters the first expansion valve 4 to reduce pressure and temperature before entering the first evaporator 5 to absorb heat from the chilled water. Subsequently, it enters the second expansion valve 6 for further pressure and temperature reduction, then passes through the second evaporator 7 to absorb heat from the fresh air, and finally returns to the compressor 1. The cooling water pump 11 is connected to the shell-and-tube condenser 3, supplying refrigerant to the condenser 3 and providing the refrigerant circulation power.

[0042] The chilled water pump 8 is connected to the first evaporator 5 and provides cooling circulation power to the first evaporator 5. The chilled water pump 8 is connected to the motor and the recovery combination cabinet 10 through the six-way valve 9. The six-way valve 9 adjusts the connection status of the chilled water pump 8 with the motor and the recovery combination cabinet 10 based on the temperature of the return air.

[0043] The cooling medium can be water or a water-based refrigerant; the specific type is not limited in this embodiment of the invention. The first expansion valve 4 and the second expansion valve 6 can be electronic expansion valves.

[0044] Specifically, the six-way valve 9 is used to connect the outlet of the chilled water pump 8 to the inlet of the recycling cabinet 10 when the temperature of the return air is lower than the outlet temperature of the cooling medium of the chilled water pump 8. The outlet of the recycling cabinet 10 is connected to the inlet of the motor, and the outlet of the motor is connected to the inlet of the chilled water pump 8.

[0045] Specifically, the six-way valve 9 is used to connect the outlet of the chilled water pump 8 to the inlet of the motor when the temperature of the return air is higher than the inlet temperature of the cooling medium of the chilled water pump 8, and to connect the outlet of the motor to the inlet of the chilled water pump 8, thereby shutting off the recovery combination cabinet 10.

[0046] Specifically, the six-way valve 9 is used to connect the outlet of the motor to the inlet of the recycling cabinet 10 when the temperature of the return air is higher than the outlet temperature of the cooling medium of the chilled water pump 8 and lower than the inlet temperature of the cooling medium of the chilled water pump 8. The outlet of the recycling cabinet 10 is connected to the inlet of the chilled water pump 8, and the outlet of the chilled water pump 8 is connected to the inlet of the motor.

[0047] In this embodiment of the invention, the switching between the three modes of the six-way valve 9—water outlet recovery of return air cooling capacity mode, water return recovery of return air cooling capacity mode, and no recovery of return air cooling capacity mode—can be determined based on the fact that the temperature of the return air is lower than the temperature of the cooling medium.

[0048] When the return air temperature is lower than the outlet temperature of the cooling medium of chilled water pump 8, the system can switch to the mode of recovering the return air cooling capacity via effluent. The six-way valve 9 connects the outlet of chilled water pump 8 to the inlet of recovery unit 10, the water outlet of recovery unit 10 to the motor inlet, and the water outlet of the motor to the inlet of chilled water pump 8. When the return air temperature is between the inlet temperature and the outlet temperature of the cooling medium of chilled water pump 8, the system can switch to the mode of recovering the return air cooling capacity via effluent. The six-way valve 9 connects the outlet of chilled water pump 8 to the water inlet of the motor, the outlet of the motor to the inlet of recovery unit 10, and the outlet of recovery unit 10 to the inlet of chilled water pump 8. When the return air temperature is higher than the inlet temperature of the cooling medium of chilled water pump 8, no cooling capacity can be recovered from the return air, and the system switches to the mode of not recovering the return air cooling capacity. The six-way valve 9 connects the outlet of the cooling medium to the motor inlet and the inlet of the cooling medium to the motor outlet, thus shutting off the recovery unit 10.

[0049] In an optional embodiment of the present invention, the tunnel boring machine cooling system further includes:

[0050] The hydraulic fan exhaust cooling tower 12 is connected to the cooling water pump 11 and the shell and tube condenser 3, and is used to cool the refrigerant in the shell and tube condenser 3; the cooling water pump 11 is used to transport the cooled refrigerant to the shell and tube condenser 3.

[0051] In this invention, the tunnel boring machine cooling system may further include a hydraulic fan exhaust air cooling tower 12. The inlet of the hydraulic fan exhaust air cooling tower 12 is connected to the shell-and-tube condenser 3, and the outlet of the hydraulic fan exhaust air cooling tower 12 is connected to a cooling water pump 11, which dissipates heat from the refrigerant absorbed by the shell-and-tube condenser 3. The cooled refrigerant is then pumped back to the shell-and-tube condenser 3 by the cooling water pump 11 for a refrigeration cycle.

[0052] Specifically, the hydraulic fan exhaust air cooling tower 12 consists of a hydraulic fan, packing material, and a water tank. The hydraulic fan drives the exhaust air flow within the hydraulic fan exhaust air cooling tower 12, driven by the hydraulic head of the refrigerant, thus saving electrical energy. The packing material enables sufficient heat and moisture exchange between the refrigerant and the air, allowing the refrigerant to release sensible heat and latent heat of vaporization into the air, achieving the purpose of temperature reduction. The water tank receives the refrigerant after heat exchange.

[0053] In an optional embodiment of the present invention, the recycling combination cabinet 10 includes:

[0054] A finned heat exchanger is used for heat exchange with the cooling medium.

[0055] A fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation.

[0056] The heat exchange unit 10 can consist of a finned heat exchanger and a fan. The finned heat exchanger uses return air to cool the cooling medium, thereby achieving heat exchange. The fan is connected to the finned heat exchanger and can operate in different modes. In the mode where return air cooling is not recovered, the fan is off; in the other two modes, the fan is on. When the fan is running, the finned heat exchanger is cooled by the return air.

[0057] This embodiment of the invention utilizes a refrigeration unit 13 and a recycling combination cabinet 10. The refrigeration unit 13 includes a compressor 1, an oil separator 2, a shell-and-tube condenser 3, a first expansion valve 4, a first evaporator 5, a second expansion valve 6, a second evaporator 7, a chilled water pump 8, a six-way valve 9, and a cooling water pump 11. The compressor 1, the oil separator 2, the shell-and-tube condenser 3, the first expansion valve 4, the first evaporator 5, the second expansion valve 6, and the second evaporator 7 are connected sequentially to form a cooling circulation loop. The second evaporator 7 is used to cool fresh air, and the cooled fresh air is used to cool the blade disc, forming return air. The cooling water pump 11 is connected to the shell-and-tube condenser 3, and the cooling water pump 11 is used to cool the blade disc and form a return air loop. The system supplies refrigerant to the shell-and-tube condenser 3; the chilled water pump 8 is connected to the first evaporator 5, and the chilled water pump 8 is connected to the motor and the recovery combination cabinet 10 through the six-way valve 9; the chilled water pump 8 is used to provide cooling medium to the motor to cool it; the six-way valve 9 is used to adjust the connection status of the chilled water pump 8 with the motor and the recovery combination cabinet 10 based on the temperature of the return air; by producing both cold air and cooling medium through a single refrigeration system, the refrigeration needs of the tunnel boring machine under two different working conditions are solved, the system complexity is reduced, and the control is more convenient; furthermore, the series arrangement of the two evaporators and the expansion valve, and the use of the recovery combination cabinet 10, reduce the energy consumption of the refrigeration system.

[0058] Reference Figure 3 This document illustrates a flowchart of an embodiment of a shield tunneling machine cooling system control method according to the present invention. The shield tunneling machine includes a motor and a cutterhead. The cooling system comprises a refrigeration unit and a recovery unit. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are sequentially connected to form a cooling circulation loop. The second evaporator is used to cool fresh air, which is then used to cool the cutterhead and form return air. The cooling water pump is connected to the shell-and-tube condenser and supplies refrigerant to it. The chilled water pump is connected to the first evaporator and is connected to the motor and the recovery unit via the six-way valve. The chilled water pump provides a cooling medium to the motor to cool it. The six-way valve adjusts the connection status of the chilled water pump with the motor and the recovery unit based on the temperature of the return air. The instruction manual for the shield tunneling machine's refrigeration system can be found in the above embodiments.

[0059] The control method for the tunnel boring machine cooling system may specifically include the following steps:

[0060] Step 301: Control the frequency of the chilled water pump based on the temperature of the cooling medium;

[0061] During the operation of the refrigeration system, the temperature of the cooling medium in the circulation loop formed by the compressor, the oil separator, the shell and tube condenser, the first expansion valve, the first evaporator, the second expansion valve, and the second evaporator is monitored in real time, and the frequency of the chilled water pump is controlled according to the temperature.

[0062] Step 302: Control the operation of the recycling combination cabinet based on the temperature of the return air.

[0063] In the embodiments of the invention, the temperature of the return air can be detected in real time during the operation of the refrigeration system, and the operation of the recycling combination cabinet can be controlled according to the temperature of the return air.

[0064] In an optional embodiment of the present invention, the step of controlling the frequency of the chilled water pump based on the temperature of the cooling medium includes: determining whether the temperature of the cooling medium is greater than a first preset temperature threshold; increasing the frequency of the chilled water pump when the temperature of the cooling medium is greater than the first preset temperature threshold; and decreasing the frequency of the chilled water pump when the temperature of the cooling medium is not greater than the first preset temperature threshold.

[0065] In this embodiment of the invention, after detecting the temperature of the cooling medium, it can be determined whether the temperature of the cooling medium is greater than a first preset temperature threshold. When the temperature of the cooling medium is greater than the first preset temperature threshold, the frequency of the chilled water pump is increased to accelerate the circulation of the cooling medium and ensure heat dissipation performance. When the temperature of the cooling medium is not greater than the first preset temperature threshold, the frequency of the chilled water pump is decreased to reduce the energy consumption of the system.

[0066] The first preset temperature threshold is a temperature reference threshold for the cooling medium, and its specific value can be determined according to the design requirements of the system. This embodiment of the invention does not limit this value.

[0067] In an optional embodiment of the present invention, the step of controlling the operation of the recycling cabinet based on the temperature of the return air includes: determining whether the temperature of the return air is greater than a second preset temperature threshold; when the temperature of the return air is greater than the second preset temperature threshold, increasing the frequency of the recycling cabinet; when the temperature of the return air is not greater than the second preset temperature threshold, decreasing the frequency of the recycling cabinet.

[0068] In this embodiment of the invention, after detecting the temperature of the cooling medium, it can be determined whether the temperature of the cooling medium is greater than a first preset temperature threshold. When the temperature of the return air is greater than a second preset temperature threshold, the frequency of the recovery unit is increased, that is, the frequency of the fan in the recovery unit is increased to ensure the heat dissipation performance of the recovery unit. When the temperature of the return air is not greater than the second preset temperature threshold, the frequency of the recovery unit is decreased, that is, the frequency of the fan in the recovery unit is reduced to reduce the energy consumption of the system.

[0069] The second preset temperature threshold is a reference temperature threshold for the return air, and its specific value can be determined according to the design requirements of the system. This embodiment of the invention does not limit this value.

[0070] The following example illustrates the control:

[0071] You can refer to Figure 4 ,in, Figure 4 In the diagram, T1 represents the cooling tower outlet air temperature, T2 the return water temperature, T3 the fresh air temperature, T4 the cooling water return temperature, T5 the outlet water temperature, T6 the supply air temperature, T7 the return air temperature, T8 the cooling water outlet temperature, and T9 the condenser outlet temperature. 10 T represents the return air temperature of the cooling tower. 11 T1 represents the outlet air temperature of the cooling tower. * To set the cooling tower outlet air temperature, T2 * To set the return water temperature, T3 * To set the fresh air temperature, T4 * To set the cooling water return temperature, T5 * To set the outlet water temperature, T6 * To set the supply air temperature, T7 * To set the return air temperature, T8 * To set the cooling water outlet temperature, T9 * To set the condenser outlet temperature, T 10 * To set the return air temperature of the cooling tower, T 11 * To set the cooling tower outlet air temperature.

[0072] After the unit is started, it checks whether the return air temperature is greater than the return water temperature. If it is, it enters the mode of not recovering the return air cooling capacity. If it is not, it checks whether the return air temperature is greater than the outlet water temperature. If it is, it enters the mode of recovering the return air cooling capacity by returning water. If it is not, it enters the mode of recovering the return air cooling capacity by returning water.

[0073] Non-recovery return air cooling mode: The recovery fan is turned off. It checks whether the cooling tower outlet air temperature is equal to the set value. If not, it checks whether the cooling tower outlet air temperature is greater than the set value. If yes, the cooling water pump frequency is increased. If not, the cooling water pump frequency is decreased. If the cooling tower outlet air temperature is equal to the set value, it checks whether the return water temperature is equal to the set value. If not, it checks whether the return water temperature is greater than the set value. If yes, the chilled water pump frequency is increased. If not, the chilled water pump frequency is decreased. If the return water temperature is equal to the set value, it checks whether the fresh air temperature is equal to the set value. If not, it checks whether the fresh air temperature is greater than the set value. If yes, the compressor frequency is increased. If not, the compressor frequency is decreased. If the fresh air temperature is equal to the set value, it enters steady-state operation.

[0074] Return water recovery and return air cooling capacity mode: The recovery fan starts and checks if the cooling water return temperature is equal to the set value. If not, it checks if the cooling water return temperature is greater than the set value. If yes, the cooling water pump frequency increases; if not, the cooling water pump frequency decreases. If the cooling water return temperature is equal to the set value, it checks if the outlet water temperature is equal to the set value. If not, it checks if the outlet water temperature is greater than the set value. If yes, the chilled water pump frequency increases; if not, the chilled water pump frequency decreases. If the outlet water temperature is equal to the set value, it checks if the supply air temperature is equal to the set value. If not, it checks if the supply air temperature is greater than the set value. If yes, the compressor frequency increases; if not, the compressor frequency decreases. If the supply air temperature is equal to the set value, it checks if the return air temperature is equal to the set value. If not, it checks if the return air temperature is greater than the set value. If yes, the recovery fan frequency increases; if not, the recovery fan frequency decreases. If the return air temperature is equal to the set value, it enters steady-state operation.

[0075] Cooling water recovery and return air cooling mode: The recovery fan starts and checks if the cooling water outlet temperature equals the set value. If not, it checks if the cooling water outlet temperature exceeds the set value. If yes, the cooling water pump frequency increases; if no, the cooling water pump frequency decreases. If the cooling water outlet temperature equals the set value, it checks if the condenser outlet temperature equals the set value. If not, it checks if the condenser outlet temperature exceeds the set value. If yes, the chilled water pump frequency increases; if no, the chilled water pump frequency decreases. If the condenser outlet temperature equals the set value... Given a set value, determine if the cooling tower return air temperature is equal to the set value. If not, determine if the cooling tower return air temperature is greater than the set value. If yes, increase the compressor frequency; if no, decrease the compressor frequency. If the cooling tower return air temperature is equal to the set value, determine if the cooling tower outlet air temperature is equal to the set value. If no, determine if the cooling tower outlet air temperature is greater than the set value. If yes, increase the recovery fan frequency; if no, decrease the recovery fan frequency. If the cooling tower outlet air temperature is equal to the set value, then enter steady-state operation.

[0076] This invention also discloses a tunnel boring machine, including: a motor, a cutterhead, and a tunnel boring machine cooling system as described above, wherein the tunnel boring machine cooling system is used to cool the motor and the cutterhead.

[0077] The tunnel boring machine cooling system includes: a refrigeration unit and a recycling combination cabinet;

[0078] The refrigeration unit includes a compressor, an oil separator, a shell and tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump;

[0079] The compressor, the oil separator, the shell and tube condenser, the first expansion valve, the first evaporator, the second expansion valve, and the second evaporator are connected in sequence to form a cooling circulation loop; the second evaporator is used to cool the fresh air, and the cooled fresh air is used to cool the blade disc and form return air; the cooling water pump is connected to the shell and tube condenser and is used to deliver refrigerant to the shell and tube condenser;

[0080] The chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recycling cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool the motor; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recycling cabinet based on the temperature of the return air.

[0081] Optionally, the six-way valve is used to connect the outlet of the chilled water pump to the inlet of the recycling cabinet when the temperature of the return air is lower than the outlet temperature of the cooling medium of the chilled water pump, the outlet of the recycling cabinet to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump.

[0082] Optionally, the six-way valve is used to connect the outlet of the chilled water pump to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump, when the temperature of the return air is higher than the inlet temperature of the cooling medium of the chilled water pump, thereby shutting off the recovery combination cabinet.

[0083] Optionally, the six-way valve is used to connect the outlet of the motor to the inlet of the recycling cabinet when the temperature of the return air is higher than the outlet temperature of the cooling medium of the chilled water pump and lower than the inlet temperature of the cooling medium of the chilled water pump. The outlet of the recycling cabinet is connected to the inlet of the chilled water pump, and the outlet of the chilled water pump is connected to the inlet of the motor.

[0084] Optionally, the tunnel boring machine cooling system further includes:

[0085] A hydraulic fan exhaust cooling tower is connected to the cooling water pump and the shell-and-tube condenser to cool the refrigerant in the shell-and-tube condenser; the cooling water pump is used to deliver the cooled refrigerant to the shell-and-tube condenser.

[0086] Optionally, the recycling combination cabinet includes:

[0087] A finned heat exchanger is used for heat exchange with the cooling medium.

[0088] A fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation.

[0089] This invention embodiment utilizes a refrigeration unit and a recycling combination cabinet. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the blade disc, forming return air. The cooling water pump is connected to the shell-and-tube condenser and is used to pump water into the shell-and-tube condenser. The system delivers refrigerant; the chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recovery combination cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool it; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recovery combination cabinet based on the temperature of the return air; by producing both cold air and cooling medium through a single refrigeration system, the cooling needs of the tunnel boring machine under two different working conditions are solved, the system complexity is reduced, and the control is more convenient; furthermore, the series arrangement of the two evaporators and the expansion valve, and the use of the recovery combination cabinet, reduce the energy consumption of the refrigeration system.

[0090] This invention also discloses an electronic device, including a processor and a storage medium, wherein the storage medium stores a computer program executable by the processor. When the electronic device is running, the processor executes the computer program to perform the tunnel boring machine cooling system control method as described in any one of the embodiments of this invention.

[0091] The tunnel boring machine (TBM) includes a motor and a cutterhead. The TBM cooling system includes a refrigeration unit and a recovery unit. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the cutterhead, forming return air. The cooling water pump is connected to the shell-and-tube condenser and is used to supply refrigerant to the shell-and-tube condenser. The chilled water pump is connected to the first evaporator and is connected to the motor and the recovery unit via the six-way valve. The chilled water pump provides a cooling medium to the motor to cool it. The six-way valve is used to adjust the connection status of the chilled water pump with the motor and the recovery unit based on the temperature of the return air. The method includes:

[0092] The frequency of the chilled water pump is controlled based on the temperature of the cooling medium.

[0093] The operation of the recycling unit is controlled based on the temperature of the return air. Optionally, the step of controlling the frequency of the chilled water pump based on the temperature of the cooling medium includes:

[0094] Determine whether the temperature of the cooling medium is greater than a first preset temperature threshold;

[0095] When the temperature of the cooling medium is greater than the first preset temperature threshold, the frequency of the chilled water pump is increased.

[0096] When the temperature of the cooling medium is not greater than the first preset temperature threshold, the frequency of the chilled water pump is reduced.

[0097] Optionally, the step of controlling the operation of the recycling cabinet based on the temperature of the return air includes:

[0098] Determine whether the temperature of the return air is greater than a second preset temperature threshold;

[0099] When the temperature of the return air is greater than the second preset temperature threshold, the frequency of the recycling combination cabinet is increased;

[0100] When the temperature of the return air is not greater than the second preset temperature threshold, the frequency of the recycling combination cabinet is reduced.

[0101] Furthermore, the six-way valve is used to connect the outlet of the chilled water pump to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump, when the temperature of the return air is higher than the inlet temperature of the cooling medium of the chilled water pump, thereby shutting off the recovery combination cabinet.

[0102] Optionally, the six-way valve is used to connect the outlet of the motor to the inlet of the recycling cabinet when the temperature of the return air is higher than the outlet temperature of the cooling medium of the chilled water pump and lower than the inlet temperature of the cooling medium of the chilled water pump. The outlet of the recycling cabinet is connected to the inlet of the chilled water pump, and the outlet of the chilled water pump is connected to the inlet of the motor.

[0103] Optionally, the tunnel boring machine cooling system further includes:

[0104] A hydraulic fan exhaust cooling tower is connected to the cooling water pump and the shell-and-tube condenser to cool the refrigerant in the shell-and-tube condenser; the cooling water pump is used to deliver the cooled refrigerant to the shell-and-tube condenser.

[0105] Optionally, the recycling combination cabinet includes:

[0106] A finned heat exchanger is used for heat exchange with the cooling medium.

[0107] A fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation.

[0108] This invention embodiment utilizes a refrigeration unit and a recycling combination cabinet. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the blade disc, forming return air. The cooling water pump is connected to the shell-and-tube condenser and is used to pump water into the shell-and-tube condenser. The system delivers refrigerant; the chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recovery combination cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool it; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recovery combination cabinet based on the temperature of the return air; by producing both cold air and cooling medium through a single refrigeration system, the cooling needs of the tunnel boring machine under two different working conditions are solved, the system complexity is reduced, and the control is more convenient; furthermore, the series arrangement of the two evaporators and the expansion valve, and the use of the recovery combination cabinet, reduce the energy consumption of the refrigeration system.

[0109] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0110] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0111] This invention also discloses a computer-readable storage medium 1101, on which a computer program is stored. When the computer program is run by a processor, it executes the shield machine cooling system control method as described in any one of the embodiments of this invention.

[0112] The tunnel boring machine (TBM) includes a motor and a cutterhead. The TBM cooling system includes a refrigeration unit and a recovery unit. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the cutterhead, forming return air. The cooling water pump is connected to the shell-and-tube condenser and is used to supply refrigerant to the shell-and-tube condenser. The chilled water pump is connected to the first evaporator and is connected to the motor and the recovery unit via the six-way valve. The chilled water pump provides a cooling medium to the motor to cool it. The six-way valve is used to adjust the connection status of the chilled water pump with the motor and the recovery unit based on the temperature of the return air. The method includes:

[0113] The frequency of the chilled water pump is controlled based on the temperature of the cooling medium.

[0114] The operation of the recycling unit is controlled based on the temperature of the return air. Optionally, the step of controlling the frequency of the chilled water pump based on the temperature of the cooling medium includes:

[0115] Determine whether the temperature of the cooling medium is greater than a first preset temperature threshold;

[0116] When the temperature of the cooling medium is greater than the first preset temperature threshold, the frequency of the chilled water pump is increased.

[0117] When the temperature of the cooling medium is not greater than the first preset temperature threshold, the frequency of the chilled water pump is reduced.

[0118] Optionally, the step of controlling the operation of the recycling cabinet based on the temperature of the return air includes:

[0119] Determine whether the temperature of the return air is greater than a second preset temperature threshold;

[0120] When the temperature of the return air is greater than the second preset temperature threshold, the frequency of the recycling combination cabinet is increased;

[0121] When the temperature of the return air is not greater than the second preset temperature threshold, the frequency of the recycling combination cabinet is reduced.

[0122] Furthermore, the six-way valve is used to connect the outlet of the chilled water pump to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump, when the temperature of the return air is higher than the inlet temperature of the cooling medium of the chilled water pump, thereby shutting off the recovery combination cabinet.

[0123] Optionally, the six-way valve is used to connect the outlet of the motor to the inlet of the recycling cabinet when the temperature of the return air is higher than the outlet temperature of the cooling medium of the chilled water pump and lower than the inlet temperature of the cooling medium of the chilled water pump. The outlet of the recycling cabinet is connected to the inlet of the chilled water pump, and the outlet of the chilled water pump is connected to the inlet of the motor.

[0124] Optionally, the tunnel boring machine cooling system further includes:

[0125] A hydraulic fan exhaust cooling tower is connected to the cooling water pump and the shell-and-tube condenser to cool the refrigerant in the shell-and-tube condenser; the cooling water pump is used to deliver the cooled refrigerant to the shell-and-tube condenser.

[0126] Optionally, the recycling combination cabinet includes:

[0127] A finned heat exchanger is used for heat exchange with the cooling medium.

[0128] A fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation.

[0129] This invention embodiment utilizes a refrigeration unit and a recycling combination cabinet. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the blade disc, forming return air. The cooling water pump is connected to the shell-and-tube condenser and is used to pump water into the shell-and-tube condenser. The system delivers refrigerant; the chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recovery combination cabinet through the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool it; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recovery combination cabinet based on the temperature of the return air; by producing both cold air and cooling medium through a single refrigeration system, the cooling needs of the tunnel boring machine under two different working conditions are solved, the system complexity is reduced, and the control is more convenient; furthermore, the series arrangement of the two evaporators and the expansion valve, and the use of the recovery combination cabinet, reduce the energy consumption of the refrigeration system.

[0130] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of the present invention are not limited to the described order of actions, because according to the embodiments of the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0131] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0132] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, embodiments of the present invention can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of the present invention can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0133] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0134] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0136] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0137] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0138] The present invention has provided a detailed description of a tunnel boring machine cooling system, a tunnel boring machine, and a control method for the tunnel boring machine cooling system. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A cooling system for a tunnel boring machine (TBM), the TBM comprising a motor and a cutterhead, characterized in that, The tunnel boring machine cooling system includes: a refrigeration unit and a recycling combination cabinet; The refrigeration unit includes a compressor, an oil separator, a shell and tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump; The compressor, the oil separator, the shell and tube condenser, the first expansion valve, the first evaporator, the second expansion valve, and the second evaporator are connected in sequence to form a cooling circulation loop; the second evaporator is used to cool the fresh air, and the cooled fresh air is used to cool the blade disc and form return air; the cooling water pump is connected to the shell and tube condenser, and the cooling water pump is used to deliver cooling water to the shell and tube condenser to cool the refrigerant inside the shell and tube condenser; The chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recycling unit via the six-way valve. The chilled water pump is used to provide cooling medium to the motor to cool it. The six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recycling unit based on the temperature of the return air. The recycling unit includes a finned heat exchanger and a fan. The finned heat exchanger is used to exchange heat with the cooling medium. The fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation.

2. The shield tunneling machine cooling system according to claim 1, characterized in that, The six-way valve is used to connect the outlet of the chilled water pump to the inlet of the recycling cabinet when the temperature of the return air is lower than the outlet temperature of the cooling medium of the chilled water pump. The outlet of the recycling cabinet is connected to the inlet of the motor, and the outlet of the motor is connected to the inlet of the chilled water pump.

3. The tunnel boring machine cooling system according to claim 2, characterized in that, The six-way valve is used to connect the outlet of the chilled water pump to the inlet of the motor, and the outlet of the motor to the inlet of the chilled water pump, when the temperature of the return air is higher than the inlet temperature of the cooling medium of the chilled water pump, thereby shutting off the recovery combination cabinet.

4. The tunnel boring machine cooling system according to claim 3, characterized in that, The six-way valve is used to connect the outlet of the motor to the inlet of the recycling cabinet when the temperature of the return air is higher than the outlet temperature of the cooling medium of the chilled water pump and lower than the inlet temperature of the cooling medium of the chilled water pump. The outlet of the recycling cabinet is connected to the inlet of the chilled water pump, and the outlet of the chilled water pump is connected to the inlet of the motor.

5. The shield machine cooling system according to claim 1, characterized in that, The tunnel boring machine cooling system also includes: A hydraulic fan exhaust cooling tower is connected to the cooling water pump and the shell-and-tube condenser to cool the refrigerant in the shell-and-tube condenser; the cooling water pump is used to deliver the cooled refrigerant to the shell-and-tube condenser.

6. A tunnel boring machine, characterized in that, include: The machine includes a motor, a cutterhead, and a tunnel boring machine cooling system as described in any one of claims 1-5, wherein the tunnel boring machine cooling system is used to cool the motor and the cutterhead.

7. A method for controlling a cooling system of a tunnel boring machine (TBM), the TBM comprising a motor and a cutterhead, characterized in that, The tunnel boring machine cooling system includes a refrigeration unit and a recovery unit. The refrigeration unit includes a compressor, an oil separator, a shell-and-tube condenser, a first expansion valve, a first evaporator, a second expansion valve, a second evaporator, a chilled water pump, a six-way valve, and a cooling water pump. The compressor, oil separator, shell-and-tube condenser, first expansion valve, first evaporator, second expansion valve, and second evaporator are connected sequentially to form a cooling circulation loop. The second evaporator is used to cool fresh air, and the cooled fresh air is used to cool the cutterhead and form return air. The cooling water pump is connected to the shell-and-tube condenser and is used to supply water to the shell-and-tube condenser. Cooling water is supplied to cool the refrigerant in the shell-and-tube condenser; the chilled water pump is connected to the first evaporator, and the chilled water pump is connected to the motor and the recovery unit via the six-way valve; the chilled water pump is used to provide cooling medium to the motor to cool it; the six-way valve is used to adjust the connection status of the chilled water pump, the motor, and the recovery unit based on the temperature of the return air; the recovery unit includes a finned heat exchanger and a fan, the finned heat exchanger is used to exchange heat with the cooling medium; the fan is connected to the finned heat exchanger and is used to dissipate heat from the finned heat exchanger during operation; the method includes: The frequency of the chilled water pump is controlled based on the temperature of the cooling medium. The operation of the recycling cabinet is controlled based on the temperature of the return air.

8. The method according to claim 7, characterized in that, The step of controlling the frequency of the chilled water pump based on the temperature of the cooling medium includes: Determine whether the temperature of the cooling medium is greater than a first preset temperature threshold; When the temperature of the cooling medium is greater than the first preset temperature threshold, the frequency of the chilled water pump is increased. When the temperature of the cooling medium is not greater than the first preset temperature threshold, the frequency of the chilled water pump is reduced.

9. The method according to claim 7, characterized in that, The step of controlling the operation of the recycling cabinet based on the temperature of the return air includes: Determine whether the temperature of the return air is greater than a second preset temperature threshold; When the temperature of the return air is greater than the second preset temperature threshold, the fan of the recycling combination cabinet is increased in frequency; When the temperature of the return air is not greater than the second preset temperature threshold, the frequency of the fan in the recycling combination cabinet is reduced.

Images