CN114754510B - Quick refrigerating system of inverse brayton low-temperature box and operation control method thereof - Google Patents
Quick refrigerating system of inverse brayton low-temperature box and operation control method thereof Download PDFInfo
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- CN114754510B CN114754510B CN202210547698.3A CN202210547698A CN114754510B CN 114754510 B CN114754510 B CN 114754510B CN 202210547698 A CN202210547698 A CN 202210547698A CN 114754510 B CN114754510 B CN 114754510B
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000005057 refrigeration Methods 0.000 claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 claims abstract description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 90
- 229910052757 nitrogen Inorganic materials 0.000 claims description 49
- 239000003570 air Substances 0.000 claims description 31
- 239000007789 gas Substances 0.000 claims description 28
- 230000017525 heat dissipation Effects 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 10
- 230000005855 radiation Effects 0.000 claims description 10
- 239000012080 ambient air Substances 0.000 claims description 4
- 238000007664 blowing Methods 0.000 claims description 4
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 3
- 238000005187 foaming Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/06—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using expanders
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/04—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type
- F25B1/053—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type of turbine type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B40/00—Subcoolers, desuperheaters or superheaters
- F25B40/06—Superheaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/40—Fluid line arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
Abstract
The invention discloses a quick refrigerating system of an inverse brayton low-temperature box, which comprises a cooler, an expander, a turbine compressor, an aftercooler and a regenerator which are sequentially and circularly communicated through pipelines, wherein the turbine compressor and the expander are driven by a high-speed motor, and the quick refrigerating system also comprises an electric control device, and the electric control device is connected with the turbine compressor and the high-speed motor; a bypass pipeline for manufacturing temporary gas short circuit phenomenon is arranged between an outlet pipeline of the aftercooler and an inlet of the turbine compressor, a bypass electromagnetic valve is arranged on the bypass pipeline, and the bypass electromagnetic valve is connected with an electric control device. The invention also discloses a corresponding operation control method. According to the invention, the running power of the turbine compressor and the high-speed motor is improved through the designed airflow short-circuit phenomenon at the initial stage of system start, and the technical scheme that the airflow short-circuit phenomenon is ended after the running power is improved is adopted, so that the purpose of rapid refrigeration is achieved through rapid improvement of the running power of the system.
Description
Technical Field
The invention relates to a gas reverse brayton cycle low-temperature box refrigeration technology, in particular to a quick refrigeration and stable operation method of a Henan new fly refrigerator with a company Limited, which is invented for solving the problems of low initial refrigeration speed and poor unit reliability of the current gas reverse brayton cycle low-temperature box.
Background
The structure of the existing inverse brayton cycle refrigeration system is as follows: the device comprises a box body for providing a low-temperature storage space, a heat regenerator for heat exchange of low-temperature nitrogen and high-temperature nitrogen, a turbine compressor, an expander, an aftercooler, a high-speed motor and a cooler positioned in the box body; the heat regenerator is provided with a high-temperature inlet, a high-temperature outlet, a low-temperature inlet and a low-temperature outlet; the foaming layer is arranged outside the heat regenerator, and the foaming layer is used for heat insulation, so that high-temperature nitrogen and low-temperature nitrogen can exchange heat better. The turbine compressor is used for compressing low-temperature low-pressure nitrogen into high-temperature high-pressure nitrogen, the air outlet of the turbine compressor is connected with a first high-temperature pipeline, the first high-temperature pipeline is connected with the inlet of the aftercooler, and the aftercooler is adjacently provided with a heat dissipation fan (preferably an axial flow fan) for blowing ambient air to the aftercooler; the outlet of the aftercooler is connected with the high-temperature inlet of the heat regenerator through a second high-temperature pipeline, the high-temperature outlet of the heat regenerator is connected with the inlet of the expansion machine through a third high-temperature pipeline, the outlet of the expansion machine is connected with a first low-temperature pipeline, the first low-temperature pipeline is connected with the inlet of the cooler, the outlet of the cooler is connected with the low-temperature inlet of the heat regenerator through a second low-temperature pipeline, and the low-temperature outlet of the heat regenerator is connected with the air inlet of the turbine compressor through a third low-temperature pipeline; the power shaft of the high-speed motor is connected with the shaft of the turbine compressor and drives the turbine compressor; the other end of the power shaft of the high-speed motor extends into the expander and is connected with an impeller (the impeller is of a conventional technology and is not shown), the inlet of the expander faces the impeller, and nitrogen passes through the third high-temperature pipeline and passes through the inlet of the expander and then impacts on the impeller to drive the power shaft of the high-speed motor to rotate. The aftercooler, the cooler and the heat regenerator are all heat exchangers. The existing reverse brayton cycle refrigerating system also comprises an electric control device, and the electric control device is connected with the turbine compressor and the high-speed motor. The shaft of the high speed motor is constrained by a pneumatic bearing (i.e., an air bearing).
In short, the structure of the existing inverse brayton cycle refrigeration system comprises a regenerator, an expander, a turbine compressor, an aftercooler and a cooler positioned in a box body, which are sequentially and circularly communicated through pipelines, wherein the turbine compressor and the expander are driven by a high-speed motor.
The disadvantage of this prior art reverse brayton cycle refrigeration system is: in the initial stage of system start, because the power of the high-speed motor is lower due to the limited air suction amount of the host, the speed of the power to be increased to the normal running level is very low, so that the performance of the turbine compressor cannot be rapidly exerted, the performance of the turbine compressor can be fully exerted after the pressure in the box is balanced for a long time, the refrigerating speed of the system is low, and the quick freezing capacity is weak.
And because the control is not perfect, the motor shaft is directly stopped in a normal working state of about 10 ten thousand revolutions per minute of the rotating speed of the high-speed motor, the motor shaft is not stable, friction can be generated at the pneumatic bearing, the pneumatic bearing and even the motor shaft are damaged, the service life of the corresponding structure is shortened, the power of the high-speed motor in subsequent use is increased, and the follow-up motor is not easy to start after the pneumatic bearing or the motor shaft is damaged.
Disclosure of Invention
The invention aims to provide a quick refrigerating system of an inverse brayton low-temperature box, which provides basic conditions for quickly exerting the performance of a turbine compressor and is beneficial to realizing quick refrigeration.
In order to achieve the aim, the quick refrigerating system of the reverse brayton low-temperature box comprises a cooler, an expander, a turbine compressor, an aftercooler and a regenerator which are sequentially and circularly communicated through pipelines, wherein the turbine compressor and the expander are driven by a high-speed motor, and the quick refrigerating system also comprises an electric control device, and the electric control device is connected with the turbine compressor and the high-speed motor; the method is characterized in that: a bypass pipeline for manufacturing temporary gas short circuit phenomenon is arranged between an outlet pipeline of the aftercooler and an inlet of the turbine compressor, a bypass electromagnetic valve is arranged on the bypass pipeline, and the bypass electromagnetic valve is connected with an electric control device.
The specific structure of the quick refrigerating system of the inverse brayton low-temperature box is as follows:
The heat regenerator is provided with a high-temperature inlet, a high-temperature outlet, a low-temperature inlet and a low-temperature outlet; the turbine compressor is used for compressing low-temperature low-pressure nitrogen into high-temperature high-pressure nitrogen, the air outlet of the turbine compressor is connected with a first high-temperature pipeline, and the first high-temperature pipeline is connected with the inlet of the aftercooler;
The aftercooler is adjacently provided with a heat dissipation fan used for blowing ambient air to the aftercooler and the high-speed motor, and the heat dissipation fan 17 is connected with an electric control device; the outlet of the aftercooler is connected with the high-temperature inlet of the heat regenerator through a second high-temperature pipeline, the high-temperature outlet of the heat regenerator is connected with the inlet of the expansion machine through a third high-temperature pipeline, the outlet of the expansion machine is connected with a first low-temperature pipeline, the first low-temperature pipeline is connected with the inlet of the cooler, the outlet of the cooler is connected with the low-temperature inlet of the heat regenerator through a second low-temperature pipeline, and the low-temperature outlet of the heat regenerator is connected with the air inlet of the turbine compressor through a third low-temperature pipeline;
the outlet end of the bypass pipeline is connected with the third low-temperature pipeline, and the inlet end of the bypass pipeline is connected with the second high-temperature pipeline.
The pipe diameter of the bypass pipeline is determined by the preset bypass flow; the total flow of the gas flowing out of the outlet of the aftercooler is SUM, and the flow of the gas passing through the bypass pipeline when the bypass electromagnetic valve is fully opened is 25% -50% of SUM.
The invention also discloses an operation control method of the quick refrigeration system of the reverse brayton low-temperature box, wherein the first step is a starting step;
When the high-speed motor is started, the electric control device starts the bypass electromagnetic valve and the heat radiation fan;
the turbine compressor and the expander driven by the high-speed motor are synchronously started when the high-speed motor is started; part of the gas flowing out of the aftercooler flows back into the turbine compressor through the bypass pipe, so that the air suction amount of the turbine compressor and the running power of the high-speed motor are rapidly improved; after the running power of the high-speed motor reaches the preset power, the electric control device closes the bypass electromagnetic valve and enters the second step;
The second step is a normal operation step; during normal operation, the turbine compressor compresses low-temperature low-pressure nitrogen to a high-temperature high-pressure state and then sends the nitrogen into a first high-temperature pipeline through an air outlet of the turbine compressor; the high-temperature nitrogen enters a high-temperature inlet of the heat regenerator through an outlet of the aftercooler and a second high-temperature pipeline; when passing through the aftercooler, high-temperature nitrogen is blown to the aftercooler and the air cooling of the high-speed motor by the heat radiation fan for cooling;
the high-temperature nitrogen enters a high-temperature outlet of the heat regenerator through a high-temperature channel in the heat regenerator, then enters an inlet of the expander through a third high-temperature pipeline, and forms a low-temperature low-pressure state after being expanded in the expander; the low-temperature nitrogen enters the cooler through the outlet of the expander and the first low-temperature pipeline, so that the temperature in the box body is reduced;
nitrogen enters a low-temperature inlet of the heat regenerator through an outlet of the cooler and a second low-temperature pipeline, and high-temperature nitrogen and low-temperature nitrogen exchange heat in the heat regenerator, so that the overall power consumption of the system is reduced, and a lower expansion temperature can be obtained; the low-temperature nitrogen enters an air inlet of the turbine compressor through a third low-temperature pipeline through a low-temperature outlet of the heat regenerator to form a complete refrigeration cycle;
the third step is a closing step; when the temperature in the box body reaches a preset low-temperature state, the electric control device turns off the high-speed motor and the heat dissipation fan.
The opening degree of the bypass electromagnetic valve is 100% when the bypass electromagnetic valve is fully opened, and the opening degree of the bypass electromagnetic valve is 0% when the bypass electromagnetic valve is closed; when the electric control device opens the bypass electromagnetic valve in the starting step, the opening degree of the bypass electromagnetic valve is 100%;
In the first step, the specific process of closing the bypass electromagnetic valve by the electric control device is as follows: dividing N times of closing operation, wherein the opening degree of each time of closing (100/N)%, N is a natural number and N is more than or equal to 5 and less than or equal to 20; the next closing operation is performed for a period of 2-30 seconds after each closing operation except for the last closing operation until the opening degree of the bypass solenoid valve is made to be 0%.
In the third step, the specific operation of electrically controlling to close the high-speed motor and the heat radiation fan is as follows:
The electric control device controls the rotation speed of the high-speed motor to be reduced according to the speed of r1 r/min, the rotation speed is less than or equal to 1000 and 200, when the rotation speed is reduced to r2, the rotation speed is less than or equal to 35000 and less than or equal to 50000, the rotation speed is continuously operated for m minutes, then the rotation speed is reduced at r3 r/min, the rotation speed is less than or equal to 100 and less than or equal to 500, and after the rotation speed is reduced to the stop point, the high-speed motor is completely closed, and meanwhile, the heat dissipation fan is closed.
The invention has the following advantages:
According to the invention, by arranging the bypass pipeline and the bypass electromagnetic valve, at the initial stage of system starting, a part of gas can flow back to the turbine compressor in a short circuit way by opening the bypass electromagnetic valve, so that the air suction amount of the turbine compressor and the power of the high-speed motor are rapidly improved to the level of normal operation; then the bypass electromagnetic valve is closed, and at the moment, the normal air suction amount of the turbine compressor is also rapidly improved under the drive of the normal power of the high-speed motor.
In short, by adopting the structure of the invention, the quick refrigerating system of the reverse brayton low-temperature box can realize the normal working state more quickly without waiting for the gradual increase of the system power after starting, thereby realizing the quick cooling function.
The invention is creative in that: when the gas short-circuit phenomenon occurs, the work done when the high-speed motor drives the gas of the short-circuit part to flow is idle work, and the avoidance of the idle work is a common technical pursuit, so that a technical scheme for intentionally creating the gas short-circuit phenomenon is not easy to think of a person skilled in the art. The inventor of the invention generally deeply thinks and carries out divergent creative thinking to obtain a technical scheme that the running power of the turbine compressor and the high-speed motor is improved through the designed airflow short-circuit phenomenon at the initial stage of system starting, and the airflow short-circuit phenomenon (the phenomenon that the high-speed motor does idle work) is ended after the running power is improved, so that the aim of rapid refrigeration is achieved by rapidly improving the running power of the system (the airflow short-circuit is needed).
The structure of the quick refrigerating system of the inverse brayton low-temperature box is the prior art except for a bypass pipeline. In the invention, the bypass pipeline is not directly connected with the outlet of the aftercooler and the inlet of the turbine compressor, but the outlet of the aftercooler and the inlet of the turbine compressor are connected through the third low-temperature pipeline and the second high-temperature pipeline so as to realize the function of partial short circuit of gas, the number of interfaces of the turbine compressor and the aftercooler is not increased, the connection is convenient, and the pressure difference of all parts of the system is utilized so as not to influence the realization of the partial short circuit function of gas.
The core of the operation control method of the invention is that the bypass electromagnetic valve is opened and closed, and the rapid improvement of the system power and the rapid cooling function are realized at the cost of short-time gas short circuit. After the system power is improved, the bypass electromagnetic valve is closed, the turbine compressor which runs at high speed can naturally keep higher air suction quantity, the time from just starting to normal operation of the system is greatly shortened, the system is promoted to work at normal level more quickly, and quick refrigeration is realized.
The bypass solenoid valve is closed for N times, and the interval between two closing operations is 2-30 seconds, so that the control method has the following advantages: if the opening degree of the bypass electromagnetic valve is closed from 100% to 0% at one time, the dynamic balance state of the high-speed motor is easily broken, so that the matched part of the shaft and the pneumatic bearing of the high-speed motor is damaged (the damaged part may be the shaft and/or the pneumatic bearing), the service life of the damaged structure is reduced, and the next high-speed motor is more difficult to start; the control method avoids the phenomenon that the dynamic balance state of the high-speed motor is broken when the high-speed motor is closed, so that the shaft and/or the pneumatic bearing are damaged.
In the invention, the scheme of gradually closing the high-speed motor in stages and finally completely closing the high-speed motor and simultaneously closing the heat dissipation fan has the advantages of two aspects. Firstly, the phenomenon that the motor shaft rotates unstably and causes friction damage between the shaft and the pneumatic bearing, which possibly occurs when the high-speed motor is directly reduced to zero from high rotating speed, can be avoided. And secondly, the heating value of the high-speed motor is continuously reduced in the gradual closing process, and the heat dissipation fan keeps normal operation, so that the high-speed motor is stably cooled, and the situation that the temperature at the high-speed motor is too high after the high-speed motor and the heat dissipation fan are directly closed is avoided.
Drawings
Fig. 1 is a schematic structural view of the present invention. The direction indicated by the arrow in fig. 1 is the flow direction of nitrogen.
Detailed Description
As shown in fig. 1, the rapid refrigeration system of the inverse brayton low-temperature box of the invention comprises a cooler 8, an expander 5, a turbine compressor 2, an aftercooler 3 and a regenerator 4 which are positioned in a box body 6 and are sequentially and circularly communicated through pipelines, wherein the turbine compressor 2 and the expander 5 are driven by a high-speed motor 1. The device also comprises an electric control device, and the electric control device is connected with the turbine compressor 2 and the high-speed motor 1; the normal operating speed of the high-speed motor 1 is 10 ten thousand revolutions per minute.
A bypass pipeline 10 for manufacturing temporary gas short circuit phenomenon is arranged between an outlet pipeline (namely a second high-temperature pipeline 11) of the aftercooler 3 and an inlet of the turbine compressor 2, a bypass electromagnetic valve 9 is arranged on the bypass pipeline 10, and the bypass electromagnetic valve 9 is connected with an electric control device. The electronic control device is conventional and is not shown.
By arranging the bypass pipeline 10 and the bypass electromagnetic valve 9, at the initial stage of system start, part of gas can flow back to the turbine compressor 2 in a short circuit way by opening the bypass electromagnetic valve 9, so that the air suction amount of the turbine compressor 2 and the power of the high-speed motor 1 are rapidly improved to the level of normal operation; then the bypass solenoid valve 9 is closed again, and at this time, the normal air suction amount of the turbine compressor 2 is also rapidly increased under the drive of the normal power of the high-speed motor 1.
In short, by adopting the structure of the invention, the quick refrigerating system of the reverse brayton low-temperature box can realize the normal working state more quickly without waiting for the gradual increase of the system power after starting, thereby realizing the quick cooling function.
The invention is creative in that: when the gas short-circuit phenomenon occurs, it means that work done when the high-speed motor 1 drives the gas flow of the short-circuit portion is idle work, and avoiding the idle work is a common technical pursuit, so that a technical scheme for intentionally creating the gas short-circuit phenomenon is not easily conceived by those skilled in the art. The inventor of the present invention generally has conducted intensive thought and divergent creative thought to obtain a technical solution of improving the operation power of the turbocompressor 2 and the high-speed motor 1 through the designed air flow short-circuit phenomenon at the initial stage of system start, and ending the air flow short-circuit phenomenon (ending the phenomenon that the high-speed motor 1 does idle work) after the operation power is improved, so as to achieve the purpose of rapid refrigeration by rapidly improving the operation power of the system (needing air flow short-circuit).
The specific structure of the quick refrigerating system of the inverse brayton low-temperature box is as follows:
Regenerator 4 has a high temperature inlet 12, a high temperature outlet 13, a low temperature inlet 14 and a low temperature outlet 15; the foaming layer is arranged outside the heat regenerator 4, and the foaming layer insulates the heat outwards, so that high-temperature nitrogen and low-temperature nitrogen are enabled to exchange heat with each other better in the heat regenerator 4. The turbine compressor 2 is used for compressing low-temperature low-pressure nitrogen into high-temperature high-pressure nitrogen, the air outlet of the turbine compressor 2 is connected with a first high-temperature pipeline 16, and the first high-temperature pipeline 16 is connected with the inlet of the aftercooler 3;
The aftercooler 3 is adjacently provided with a heat radiation fan 17 (preferably an axial flow fan) for blowing ambient air to the aftercooler 3 and the high-speed motor 1; the outlet of the aftercooler 3 is connected with the high-temperature inlet 12 of the regenerator 4 through a second high-temperature pipeline 11, the high-temperature outlet 13 of the regenerator 4 is connected with the inlet of the expander 5 through a third high-temperature pipeline, the outlet of the expander 5 is connected with a first low-temperature pipeline 18, the first low-temperature pipeline 18 is connected with the inlet of the cooler 8, the outlet of the cooler 8 is connected with the low-temperature inlet 14 of the regenerator 4 through a second low-temperature pipeline 19, and the low-temperature outlet 15 of the regenerator 4 is connected with the air inlet of the turbine compressor 2 through a third low-temperature pipeline 20; the aftercooler 3, the service cooler 8 and the regenerator 4 are all heat exchangers. The heat radiation fan 17 is connected with an electric control device.
The outlet end of the bypass line 10 is connected to a third low temperature line 20 and the inlet end of the bypass line 10 is connected to a second high temperature line 11.
The construction of the inverse brayton low temperature tank flash refrigeration system is prior art except for the bypass line 10. In the invention, the bypass pipeline 10 is not directly connected with the outlet of the aftercooler 3 and the inlet of the turbine compressor 2, but the outlet of the aftercooler 3 and the inlet of the turbine compressor 2 are connected through the third low-temperature pipeline 20 and the second high-temperature pipeline 11 so as to realize the function of partial short circuit of gas, the number of interfaces of the turbine compressor 2 and the aftercooler 3 is not increased, the connection is convenient, and the pressure difference of the system is utilized without influencing the realization of the partial short circuit function of gas.
The pipe diameter of the bypass pipe 10 is determined by a preset bypass flow; the total flow of the gas flowing out of the outlet of the aftercooler 3 is SUM, and the flow of the gas passing through the bypass pipeline 10 when the bypass electromagnetic valve 9 is fully opened is 25% -50% (including two end values) of SUM. According to the bypass flow target, the pipe diameter of the bypass pipeline 10 is 50-70% of that of the second high-temperature pipeline 11.
The invention also discloses an operation control method of the quick refrigeration system of the reverse brayton low-temperature box.
The first step is a start-up step;
The electric control device opens the bypass electromagnetic valve 9 and the heat radiation fan 17 while the high-speed motor 1 is opened;
The turbine compressor 2 and the expander 5 driven by the high-speed motor 1 are synchronously started when the high-speed motor is started; part of the gas flowing out of the aftercooler 3 flows back into the turbine compressor 2 through the bypass pipeline 10, so that the air suction amount of the turbine compressor 2 and the operating power of the high-speed motor 1 are rapidly improved; after the running power of the high-speed motor 1 reaches the preset power, the electric control device closes the bypass electromagnetic valve 9 and enters a second step;
The second step is a normal operation step; in normal operation, the turbine compressor 2 compresses low-temperature low-pressure nitrogen to a high-temperature high-pressure state and then sends the nitrogen to the first high-temperature pipeline 16 through the air outlet of the turbine compressor 2; the high-temperature nitrogen gas then enters a high-temperature inlet 12 of the heat regenerator 4 through an outlet of the aftercooler 3 and a second high-temperature pipeline 11; when passing through the aftercooler 3, high-temperature nitrogen is blown to the aftercooler 3 and the air cooling of the high-speed motor 1 by the heat radiation fan 17 for cooling;
The high-temperature nitrogen enters a high-temperature outlet 13 of the heat regenerator 4 through a high-temperature channel 21 in the heat regenerator 4, then enters an inlet of the expander 5 through a third high-temperature pipeline, and forms a low-temperature low-pressure state after being expanded in the expander 5; the low-temperature nitrogen enters the cooler 8 through the outlet of the expander 5 and the first low-temperature pipeline 18, so that the temperature in the box 6 is reduced;
The nitrogen enters the low-temperature inlet 14 of the heat regenerator 4 through the outlet of the cooler 8 and the second low-temperature pipeline 19, and the high-temperature nitrogen and the low-temperature nitrogen exchange heat in the heat regenerator 4, so that the overall power consumption of the system is reduced, and a lower expansion temperature can be obtained; the low-temperature nitrogen enters a low-temperature outlet 15 of the heat regenerator 4 through a low-temperature channel 22 in the heat regenerator 4, and the low-temperature nitrogen enters an air inlet of the turbine compressor 2 through a third low-temperature pipeline 20 through the low-temperature outlet 15 of the heat regenerator 4 to form a complete refrigeration cycle;
the third step is a closing step; when the temperature in the case 6 reaches a predetermined low temperature state (the case 6 is provided with a temperature sensor 7 connected to an electric control device, which is a conventional technology and will not be described in detail), the electric control device turns off the high-speed motor 1 and the heat dissipation fan 17.
The core of the operation control method of the invention is that the bypass electromagnetic valve 9 is opened and closed, and the rapid improvement of the system power and the rapid cooling function are realized at the cost of short-time gas short circuit. After the system power is improved, the bypass electromagnetic valve 9 is closed, the turbine compressor 2 which runs at high speed can naturally keep higher air suction quantity, the time from just starting to normal operation of the system is greatly shortened, the system is promoted to work at normal level more quickly, and quick refrigeration is realized.
The bypass solenoid valve 9 has an opening degree of 100% when fully opened and an opening degree of 0% when closed; when the electric control device opens the bypass electromagnetic valve 9 in the starting step, the opening degree of the bypass electromagnetic valve 9 is made to be 100%;
in the first step, the specific process of closing the bypass electromagnetic valve 9 by the electric control device is as follows: dividing N times of closing operation, wherein the opening degree of each time of closing (100/N)%, N is a natural number and N is more than or equal to 5 and less than or equal to 20; the next closing operation is performed for a period of 2 to 30 seconds (inclusive) after each closing operation except for the last closing operation until the opening degree of the bypass solenoid valve 9 is made 0%.
The bypass solenoid valve 9 is closed for N times, and the interval between the two closing operations is 2-30 seconds, so that the control method has the following advantages: if the opening degree of the bypass solenoid valve 9 is closed from 100% to 0% at a time, the dynamic balance state of the high-speed motor 1 is easily broken, so that the part of the shaft of the high-speed motor 1 matched with the pneumatic bearing is damaged (the damaged part may be the shaft and/or the pneumatic bearing), the service life of the damaged structure is reduced, and the next starting of the high-speed motor 1 is more difficult; the control method avoids the phenomenon that the dynamic balance state of the high-speed motor 1 is broken when the motor is closed, so that the shaft and/or the pneumatic bearing are damaged.
In the third step, the specific operation of electrically controlling to turn off the high-speed motor 1 and the heat dissipation fan 17 is as follows:
The electric control device controls the rotation speed of the high-speed motor 1 to decrease according to the rotation speed of r1 r/min, the rotation speed of r1 is less than or equal to 1000 and 200, when the rotation speed is reduced to r2, the rotation speed of r2 is less than or equal to 35000 and less than or equal to 50000, the rotation speed is continuously operated for m minutes, then the rotation speed is reduced to r3 r/min, the rotation speed of r3 is less than or equal to 500, and after the rotation speed is reduced to the stop point, the high-speed motor 1 is completely closed, and meanwhile, the heat dissipation fan 17 is closed. Wherein r1, r2 and r3 are natural numbers.
In the invention, the scheme of gradually closing the high-speed motor 1 in stages and finally completely closing the high-speed motor 1 and simultaneously closing the heat dissipation fan 17 has the advantages of two aspects. Firstly, the phenomenon that the motor shaft of the high-speed motor 1 is not stable in rotation and the friction between the shaft and the pneumatic bearing is caused when the rotation speed of the motor is reduced to zero directly can be avoided. Secondly, the heating value of the high-speed motor 1 is continuously reduced in the gradual closing process, and the heat dissipation fan 17 keeps normal operation, so that the high-speed motor 1 is stably cooled, and the situation that the temperature at the high-speed motor 1 is too high after the high-speed motor 1 and the heat dissipation fan 17 are directly closed is avoided.
The above embodiments are only for illustrating the technical solution of the present invention, and it should be understood by those skilled in the art that although the present invention has been described in detail with reference to the above embodiments: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention, which is intended to be encompassed by the claims.
Claims (4)
1. The operation control method of the quick refrigerating system of the inverse brayton low-temperature box comprises a cooler, an expander, a turbine compressor, an aftercooler and a regenerator which are sequentially and circularly communicated through pipelines and positioned in the box body, wherein the turbine compressor and the expander are driven by a high-speed motor, and the quick refrigerating system also comprises an electric control device, and the electric control device is connected with the turbine compressor and the high-speed motor; the method is characterized in that: a bypass pipeline for manufacturing temporary gas short circuit phenomenon is arranged between an outlet pipeline of the aftercooler and an inlet of the turbine compressor, a bypass electromagnetic valve is arranged on the bypass pipeline, and the bypass electromagnetic valve is connected with an electric control device;
The specific structure of the quick refrigerating system of the inverse brayton low-temperature box is as follows:
The heat regenerator is provided with a high-temperature inlet, a high-temperature outlet, a low-temperature inlet and a low-temperature outlet; the turbine compressor is used for compressing low-temperature low-pressure nitrogen into high-temperature high-pressure nitrogen, the air outlet of the turbine compressor is connected with a first high-temperature pipeline, and the first high-temperature pipeline is connected with the inlet of the aftercooler;
The aftercooler is adjacently provided with a heat dissipation fan used for blowing ambient air to the aftercooler and the high-speed motor, and the heat dissipation fan 17 is connected with an electric control device; the outlet of the aftercooler is connected with the high-temperature inlet of the heat regenerator through a second high-temperature pipeline, the high-temperature outlet of the heat regenerator is connected with the inlet of the expansion machine through a third high-temperature pipeline, the outlet of the expansion machine is connected with a first low-temperature pipeline, the first low-temperature pipeline is connected with the inlet of the cooler, the outlet of the cooler is connected with the low-temperature inlet of the heat regenerator through a second low-temperature pipeline, and the low-temperature outlet of the heat regenerator is connected with the air inlet of the turbine compressor through a third low-temperature pipeline;
the outlet end of the bypass pipeline is connected with a third low-temperature pipeline, and the inlet end of the bypass pipeline is connected with a second high-temperature pipeline;
The first step is a start-up step;
When the high-speed motor is started, the electric control device starts the bypass electromagnetic valve and the heat radiation fan;
the turbine compressor and the expander driven by the high-speed motor are synchronously started when the high-speed motor is started; part of the gas flowing out of the aftercooler flows back into the turbine compressor through the bypass pipe, so that the air suction amount of the turbine compressor and the running power of the high-speed motor are rapidly improved; after the running power of the high-speed motor reaches the preset power, the electric control device closes the bypass electromagnetic valve and enters the second step;
The second step is a normal operation step; during normal operation, the turbine compressor compresses low-temperature low-pressure nitrogen to a high-temperature high-pressure state and then sends the nitrogen into a first high-temperature pipeline through an air outlet of the turbine compressor; the high-temperature nitrogen enters a high-temperature inlet of the heat regenerator through an outlet of the aftercooler and a second high-temperature pipeline; when passing through the aftercooler, high-temperature nitrogen is blown to the aftercooler and the air cooling of the high-speed motor by the heat radiation fan for cooling;
the high-temperature nitrogen enters a high-temperature outlet of the heat regenerator through a high-temperature channel in the heat regenerator, then enters an inlet of the expander through a third high-temperature pipeline, and forms a low-temperature low-pressure state after being expanded in the expander; the low-temperature nitrogen enters the cooler through the outlet of the expander and the first low-temperature pipeline, so that the temperature in the box body is reduced;
nitrogen enters a low-temperature inlet of the heat regenerator through an outlet of the cooler and a second low-temperature pipeline, and high-temperature nitrogen and low-temperature nitrogen exchange heat in the heat regenerator, so that the overall power consumption of the system is reduced, and a lower expansion temperature can be obtained; the low-temperature nitrogen enters an air inlet of the turbine compressor through a third low-temperature pipeline through a low-temperature outlet of the heat regenerator to form a complete refrigeration cycle;
the third step is a closing step; when the temperature in the box body reaches a preset low-temperature state, the electric control device turns off the high-speed motor and the heat dissipation fan.
2. The operation control method according to claim 1, characterized in that: the pipe diameter of the bypass pipeline is determined by the preset bypass flow; the total flow of the gas flowing out of the outlet of the aftercooler is SUM, and the flow of the gas passing through the bypass pipeline when the bypass electromagnetic valve is fully opened is 25% -50% of SUM.
3. The operation control method according to claim 2, characterized in that: the opening degree of the bypass electromagnetic valve is 100% when the bypass electromagnetic valve is fully opened, and the opening degree of the bypass electromagnetic valve is 0% when the bypass electromagnetic valve is closed; when the electric control device opens the bypass electromagnetic valve in the starting step, the opening degree of the bypass electromagnetic valve is 100%;
In the first step, the specific process of closing the bypass electromagnetic valve by the electric control device is as follows: dividing N times of closing operation, wherein the opening degree of each time of closing (100/N)%, N is a natural number and N is more than or equal to 5 and less than or equal to 20; the next closing operation is performed for a period of 2-30 seconds after each closing operation except for the last closing operation until the opening degree of the bypass solenoid valve is made to be 0%.
4. The operation control method according to claim 2, characterized in that:
In the third step, the specific operation of electrically controlling to close the high-speed motor and the heat radiation fan is as follows:
The electric control device controls the rotation speed of the high-speed motor to be reduced according to the speed of r1 r/min, the rotation speed is less than or equal to 1000 and 200, when the rotation speed is reduced to r2, the rotation speed is less than or equal to 35000 and less than or equal to 50000, the rotation speed is continuously operated for m minutes, then the rotation speed is reduced at r3 r/min, the rotation speed is less than or equal to 100 and less than or equal to 500, and after the rotation speed is reduced to the stop point, the high-speed motor is completely closed, and meanwhile, the heat dissipation fan is closed.
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| CN202210547698.3A CN114754510B (en) | 2022-05-20 | 2022-05-20 | Quick refrigerating system of inverse brayton low-temperature box and operation control method thereof |
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| CN113865135A (en) * | 2021-08-23 | 2021-12-31 | 中国北方车辆研究所 | Tank armored vehicle air expansion refrigeration system and method utilizing open type inverse Brayton cycle |
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| EP3088682B1 (en) * | 2015-04-29 | 2017-11-22 | General Electric Technology GmbH | Control concept for closed brayton cycle |
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| CN106256275A (en) * | 2016-10-14 | 2016-12-28 | 上海朗旦制冷技术有限公司 | The portable air cooling air-conditioned clothes of swell refrigeration |
| CN111351290A (en) * | 2020-04-28 | 2020-06-30 | 河南新飞制冷器具有限公司 | Domestic ultra-low temp refrigerator |
| CN214307672U (en) * | 2020-11-16 | 2021-09-28 | 四川航天计量测试研究所 | Reverse Brayton air refrigeration system adopting hot gas defrosting |
| CN112484330A (en) * | 2020-12-28 | 2021-03-12 | 河南新飞制冷器具有限公司 | Brayton refrigeration cycle low-temperature box |
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| CN114754510A (en) | 2022-07-15 |
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