CN113513852A - Cooling system, refrigeration equipment and cooling method - Google Patents
Cooling system, refrigeration equipment and cooling method Download PDFInfo
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- CN113513852A CN113513852A CN202110812075.XA CN202110812075A CN113513852A CN 113513852 A CN113513852 A CN 113513852A CN 202110812075 A CN202110812075 A CN 202110812075A CN 113513852 A CN113513852 A CN 113513852A
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- 238000001816 cooling Methods 0.000 title claims abstract description 166
- 238000005057 refrigeration Methods 0.000 title claims abstract description 51
- 230000006835 compression Effects 0.000 claims abstract description 19
- 238000007906 compression Methods 0.000 claims abstract description 19
- 239000000498 cooling water Substances 0.000 claims abstract description 7
- 239000003507 refrigerant Substances 0.000 claims description 23
- 238000004804 winding Methods 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 19
- 238000009833 condensation Methods 0.000 claims description 17
- 238000004781 supercooling Methods 0.000 claims description 17
- 230000005494 condensation Effects 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000001704 evaporation Methods 0.000 claims description 10
- 230000008020 evaporation Effects 0.000 claims description 10
- 238000010992 reflux Methods 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 5
- 238000004891 communication Methods 0.000 claims description 3
- 230000007774 longterm Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 4
- 238000000034 method Methods 0.000 description 3
- 239000000110 cooling liquid Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 206010016754 Flashback Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
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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
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
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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
- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K9/00—Arrangements for cooling or ventilating
- H02K9/19—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
- H02K9/193—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil with provision for replenishing the cooling medium; with means for preventing leakage of the cooling medium
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K9/00—Arrangements for cooling or ventilating
- H02K9/19—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
- H02K9/20—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil wherein the cooling medium vaporises within the machine casing
Abstract
The invention provides a cooling system, refrigeration equipment and a cooling method, relates to the technical field of refrigeration equipment, and solves the technical problems that the cooling capacity of the cooling system is not adjustable, the refrigeration effect is common in high-pressure ratio and the refrigeration capacity is wasted in low-pressure ratio. The cooling system comprises a first cooling unit and a second cooling unit which are arranged between a condenser and a compressor in parallel, wherein the first cooling unit and the second cooling unit refrigerate in a partial operation mode or a whole operation mode; the refrigerating equipment comprises an evaporator, a compressor, a condenser, a flash evaporator, a primary electronic expansion valve, a secondary electronic expansion valve and a cooling system, wherein the evaporator, the compressor, the condenser and the flash evaporator are sequentially connected through pipelines, the primary electronic expansion valve is arranged between the condenser and the flash evaporator, the secondary electronic expansion valve is arranged between the flash evaporator and the evaporator, and the cooling system is arranged between the condenser and the compressor. The invention ensures the sufficient and reasonable cooling of the motor under different working conditions in the double-stage compression cooling water unit system and ensures the long-term stable operation of the unit.
Description
Technical Field
The invention relates to the technical field of refrigeration equipment, in particular to a cooling system, refrigeration equipment and a cooling method.
Background
In a large-scale refrigeration system, as the unit operates for a long time and the load increases, the heat of a compressor motor in the system also increases, and the motor needs to be cooled at any moment in order to ensure the normal operation and the long-term reliable operation of the compressor motor. For a large-scale refrigeration system, a centrifugal water chilling unit is usually adopted as common refrigeration equipment, double-stage compression is one of common refrigeration circulation modes, the double-stage compression system can be applied to various working conditions except refrigeration, such as working conditions of ice storage, a heat pump and the like, meanwhile, the exhaust temperature of a high-pressure-stage compressor can be reduced through a double-stage compression middle air supply mode, the total power consumption of the compressor is further reduced, the performance of the system is improved, and the pressure ratio of the compressor in the double-stage compression refrigeration circulation system is relatively higher. Under the working conditions of ice storage or heat pump, the system adopts single-stage compression or multi-stage compression, the temperature difference between the condensation temperature and the evaporation temperature is large, namely, under the working conditions of ice storage or heat pump, the pressure ratio of the compressor is higher than that under the working condition of refrigeration.
Under the working condition of higher pressure ratio, the cooling of the motor is particularly important in consideration of the fact that the heat generated by the motor is relatively more, and if the cooling capacity of the motor is insufficient, the phenomenon that the winding temperature in the motor is too high, the motor is burnt and the motor is stopped can be caused.
The cooling mode commonly used at present is that liquid refrigerant is taken from the bottom of a condenser and filtered by a filter, and is throttled and depressurized by a throttling device, then the motor is cooled, the refrigerant absorbs heat in the cooling process and becomes gaseous, and finally the gaseous refrigerant enters a flash evaporator or an evaporator in a unit. The cooling mode can be applied to a conventional refrigeration system, but the cooling capacity of the water chilling unit under the working condition of large pressure ratio is slightly insufficient, and the cooled return air enters the evaporator or the flash evaporator under the working condition of different pressure ratios and is reasonably designed and controlled.
To sum up, to the doublestage compression system, no matter be refrigeration operating mode, ice-storage operating mode or heat pump operating mode, its pressure ratio all is higher relatively, and the motor calorific capacity that leads to promptly also can be higher relatively, so in order to ensure that doublestage compression system can carry out long-term stable operation under various different operating modes, provided a new cooling method, the high-efficient reliable operation of guarantee unit.
Disclosure of Invention
The invention aims to provide a cooling system, a refrigeration device and a cooling method, and aims to solve the technical problems that the cooling capacity of the cooling system is not adjustable, the refrigeration effect is common in a high-pressure ratio and the refrigeration quantity is wasted in a low-pressure ratio in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention provides a cooling system which comprises a first cooling unit and a second cooling unit which are arranged between a condenser and a compressor in parallel, wherein the first cooling unit and the second cooling unit refrigerate in a partial operation mode or a whole operation mode.
As a further development of the invention, the first cooling unit is in a manual adjustment mode and the second cooling unit is in an automatic adjustment mode.
As a further development of the invention, the first cooling unit comprises a manually controllable ball valve and a first orifice plate connected by a pipeline.
As a further improvement of the present invention, the second cooling unit includes a second orifice plate and an electronic expansion valve connected by a pipe.
As a further improvement of the present invention, the compressor is a two-stage compressor, and includes a low-pressure stage compressor and a high-pressure stage compressor, and both the first cooling unit and the second cooling unit are connected to the two-stage compressor; the outlet side of the electronic expansion valve is also provided with three branches in parallel, and each branch is provided with an electromagnetic valve; wherein two of the branches are connected to the high pressure stage compressor and one of the branches is connected to the low pressure stage compressor.
As a further improvement of the invention, the flash evaporator further comprises a backflow unit, wherein the backflow unit comprises a first backflow unit and a second backflow unit which are arranged in parallel, and two ends of the first backflow unit are respectively connected with the compressor and the flash tank; and two ends of the second backflow unit are respectively connected with the compressor and the evaporator.
As a further improvement of the present invention, electromagnetic valves are disposed on both the first and second backflow units.
As a further improvement of the present invention, the present invention further comprises a detection element, wherein the detection element comprises a motor winding temperature sensor arranged on the compressor, an exhaust gas temperature sensor arranged on the outlet side of the high-pressure stage compressor, a condensation pressure sensor arranged on the condenser, a cooling water outlet temperature sensor and a condenser outlet temperature sensor, and an evaporation pressure sensor arranged on the evaporator.
The invention provides refrigeration equipment which comprises an evaporator, a compressor, a condenser, a flash evaporator, a primary electronic expansion valve, a secondary electronic expansion valve and a cooling system, wherein the evaporator, the compressor, the condenser and the flash evaporator are sequentially connected through pipelines, the primary electronic expansion valve is arranged between the condenser and the flash evaporator, the secondary electronic expansion valve is arranged between the flash evaporator and the evaporator, and the cooling system is arranged between the condenser and the compressor.
As a further improvement of the present invention, the compressor is a two-stage compressor, including a low-pressure stage compressor and a high-pressure stage compressor.
As a further improvement of the invention, the refrigeration equipment is a two-stage compression type water chilling unit.
The invention provides a cooling method for cooling refrigeration equipment, which comprises the following steps:
step 100, starting refrigeration equipment to carry out conventional refrigeration;
step 200, controlling a first cooling unit and/or a second cooling unit to start to cool a motor in a compressor according to the running state of the refrigeration equipment;
and step 300, controlling the cooled liquid to flow back to the evaporator or the flash tank according to the running state of the refrigeration equipment.
As a further improvement of the present invention, in step 200, the operation state of the refrigeration equipment includes that the compressor is in a high pressure ratio operation state, the compressor is in a low pressure ratio operation state, the motor in the compressor is in an overheat state, and the motor in the compressor is in a condensation state.
As a further improvement of the present invention, when only one of the two-stage compressors is operated, one of the three branches located between the electronic expansion valve and the compressor is in a communicating state; when two compressors in the two-stage compressor run and are in a low-pressure ratio running state, two branches in the three branches between the electronic expansion valve and the compressors are in a communicated state; when two compressors in the two-stage compressor are both in operation and in a high pressure ratio operation state, all three branches are in a communication state.
As a further improvement of the invention, when the compressor is in a high pressure ratio operation state, the cooled liquid flows back to the evaporator; when the compressor is in a low pressure ratio operating state, the cooled liquid flows back to the flash tank.
As a further improvement of the invention, the high pressure ratio operation state of the compressor is that when the pressure ratio epsilon of the compressor is more than or equal to 1.5, and the low pressure ratio operation state of the compressor is that epsilon is less than 1.5.
As a further improvement of the present invention, in step 200, the first cooling unit is in a manual adjustment mode, and the refrigerant flow rate is adjusted by manually adjusting the opening degree of a manually controllable ball valve in the first cooling unit, wherein the opening degree range of the manually controllable ball valve is 0% to 100%.
As a further improvement of the present invention, in step 200, the second cooling unit is in an automatic adjustment mode, and the method includes the following adjustment steps:
step A: in the shutdown state of the refrigeration equipment, the target opening degree of the electronic expansion valve in the second cooling unit is 0 percent;
and B: starting the refrigeration equipment, and automatically adjusting the opening of the electronic expansion valve to 50% for 3 min;
and C: the electronic expansion valve enters an automatic adjusting mode and is adjusted according to parameters of motor winding temperature difference delta Tj, pressure ratio epsilon, supercooling degree delta Tsc, exhaust superheat degree delta Td and condenser end temperature difference delta Tc;
step D: when the pressure ratio epsilon is more than or equal to 1.5, the minimum value of the target opening of the electronic expansion valve is 0 percent, and the maximum value of the target opening is 100 percent; when the pressure ratio epsilon is less than 1.5, the minimum value of the target opening degree of the electronic expansion valve is 0%, the maximum value of the target opening degree is 50%, the electronic expansion valve is controlled to execute an action every 5s by utilizing the parameters of the supercooling degree delta Tsc, the temperature difference delta Tc of the condenser end and the exhaust superheat degree delta Td, the action amplitude does not exceed 3% every time, and the calculation formula of the action amplitude is as follows: D-D1 + D2+ D3+ D4;
when D is larger than 0.5, the target opening degree of the electronic expansion valve is increased by D%;
when D is more than or equal to 0.5 and more than or equal to-0.5, the target opening of the electronic expansion valve is kept unchanged;
when D < -0.5, the target opening degree of the electronic expansion valve is reduced by D%;
step E: the refrigerating equipment is stopped, and the target opening degree of the electronic expansion valve is changed from the current opening degree to 0%.
As a further improvement of the invention, the calculation formulas of D1, D2, D3 and D4 in the action amplitude are as follows:
when the winding temperature difference delta Tj of the motor is more than or equal to 4 ℃, D1 is 0.6 (delta Tsc-4);
when the motor winding temperature difference delta Tj is less than 4 ℃, D1 is 0.2 (delta Tsc-4);
when the supercooling degree delta Tsc is more than or equal to 2.5 ℃, D2 is 0.3 (delta Tsc-2.5);
when the degree of supercooling Δ Tsc is <2.5 ℃, D2 is 0.8 ═ 2.5 (Δ Tsc-2.5);
when the temperature difference delta Tc at the end of the condenser is less than or equal to 1 ℃, D3 is 0;
when the condenser end temperature difference Δ Tc >1 ℃, D3 is 0.5 ═ Δ Tc-1;
when the exhaust superheat degree delta Td is more than or equal to 3.5 ℃, D4 is 0.3 (delta Td-3.5);
when the exhaust superheat degree Δ Td is less than 3.5 ℃, D4 is 0.9 × (Δ Td-3.5).
Compared with the prior art, the invention has the following beneficial effects:
the cooling system provided by the invention is applied to a two-stage compression water chilling unit, and two sets of cooling units can be selected to participate in cooling of the compressor motor or all the cooling units participate in cooling of the motor, so that sufficient and reasonable cooling of the motor under different working conditions in the two-stage compression water chilling unit system is guaranteed; the shutdown caused by burning out of the motor winding is avoided, the condensation caused by supercooling of the motor is avoided, and the long-term stable operation of the unit is ensured; by arranging the two backflow units in parallel, the cooling liquid is controlled to flow back into the evaporator or the flash evaporator under different running states of the equipment, so that the reasonable cooling of the motor is guaranteed, and meanwhile, the uncertainty that refrigerants enter the evaporator or the flash evaporator under different working conditions is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a logical wiring diagram of the cooling system of the present invention.
FIG. 1, a low pressure stage compressor; 2. a high pressure stage compressor; 3. a condenser; 4. a first-stage electronic expansion valve; 5. a flash tank; 6. a secondary electronic expansion valve; 7. an evaporator; 8. a manually controllable ball valve; 9. a first orifice plate; 10. a fourth solenoid valve; 11. a fifth solenoid valve; 12. a second orifice plate; 13. an electronic expansion valve; 14. a first solenoid valve; 15. a second solenoid valve; 16. a third electromagnetic valve; 17. a condensing pressure sensor; 18. a cooling water outlet temperature sensor; 19. a condenser outlet liquid temperature sensor; 20. an evaporation pressure sensor; 21. an exhaust gas temperature sensor; 22. and a motor winding temperature sensor.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
As shown in fig. 1, the present invention provides a cooling system including a first cooling unit and a second cooling unit disposed in parallel between a condenser 3 and a compressor, the first cooling unit and the second cooling unit performing cooling in a partial operation or a full operation.
A cooling unit is arranged between the condenser 3 and the compressor to cool the motor by utilizing a liquid refrigerant at the bottom of the condenser; by arranging the two sets of cooling units connected in parallel, one set of cooling unit can be selected to participate in cooling according to the running condition of the equipment, or the two sets of cooling units are selected to participate in cooling together, so that the cooling capacity of the cooling system is adjustable, the good cooling effect is ensured when the equipment runs at a high pressure ratio, and the cold energy is not wasted when the equipment runs at a low pressure ratio.
As a further alternative embodiment of the invention, the first cooling unit is in manual adjustment mode and the second cooling unit is in automatic adjustment mode. When the cooling system is used, the second cooling unit mainly depends on the automatic adjusting mode to carry out cooling, and when the cooling capacity of the second cooling unit is insufficient, the first cooling unit can be manually started to improve the cooling capacity of the cooling system.
Further, the first cooling unit comprises a manually controllable ball valve 8 and a first orifice plate 9 connected by a pipeline.
Wherein the opening range of the manual controllable ball valve 8 is 0-100%. The aperture of the first throttling orifice plate 9 is designed according to the cooling capacity required by the motor under the design working condition, and the fixed throttling and cooling effects are achieved.
Further, the second cooling unit includes a second orifice 12 and an electronic expansion valve 13 connected by a pipe.
As an optional embodiment of the present invention, the compressor is a two-stage compressor, and includes a low-pressure stage compressor 1 and a high-pressure stage compressor 2, and the first cooling unit and the second cooling unit are both connected to the two-stage compressor and used for cooling the two-stage compressor and the middle motor; furthermore, the outlet side of the electronic expansion valve 13 is also provided with three branches in parallel, each branch is provided with an electromagnetic valve, specifically, the three branches are respectively a first branch, a second branch and a third branch, the first branch is provided with a first electromagnetic valve 14, the second branch is provided with a second electromagnetic valve 15, and the third branch is provided with a third electromagnetic valve 16; two branches, namely a first branch and a second branch, are connected to the high-pressure stage compressor 2, and one branch, namely a third branch, is connected to the low-pressure stage compressor 1.
Furthermore, the flash evaporator also comprises a backflow unit, wherein the backflow unit comprises a first backflow unit and a second backflow unit which are arranged in parallel, and two ends of the first backflow unit are respectively connected with the compressor and the flash evaporator 5; the two ends of the second reflux unit are respectively connected with the compressor and the evaporator 7.
It should be noted that the first and second return units are both provided with solenoid valves, that is, the first return unit is provided with a fourth solenoid valve 10, and the second return unit is provided with a fifth solenoid valve 11.
As an alternative embodiment of the present invention, the present invention further comprises a detection element, wherein the detection element comprises a motor winding temperature sensor 22 arranged on the compressor, an exhaust gas temperature sensor 21 arranged on the outlet side of the high-pressure stage compressor 2, a condensation pressure sensor 17 arranged on the condenser 3, a cooling water outlet temperature sensor 18 and a condenser outlet temperature sensor 19, and an evaporation pressure sensor 20 arranged on the evaporator 7.
As shown in fig. 1, the cooling system is a cooling system for a two-stage compression refrigeration system with motor cooling and air return, a low-temperature low-pressure gaseous refrigerant from an evaporator 7 is sucked by a low-pressure stage compressor 1, compressed, mixed with air supplement at an upper outlet of a flash tank 5, sucked by a high-pressure stage compressor 2, compressed for the second time, and a high-temperature high-pressure gaseous refrigerant from the high-pressure stage compressor 2 enters a condenser 3 for condensation, wherein an exhaust temperature sensor 21 is installed on an exhaust pipe of the high-pressure stage compressor 2 for detecting an exhaust temperature Td of the high-pressure stage compressor 2, motor winding temperature sensors 22 are installed on motors of the two sets of compressors for monitoring the temperature of the motors, the condenser 3 is a horizontal shell-tube condenser, a supercooling region exists at the lower part, and a condensing pressure sensor 17 is installed on the condenser 3, the condenser is used for detecting the condensation pressure Pc of the system, the corresponding condensation temperature Tc can be calculated through the controller, and meanwhile, the condenser 3 is also provided with a cooling water outlet temperature sensor 18 and a condenser outlet temperature sensor 19, and the cooling outlet temperature Tco and the condenser outlet temperature Tsc can be respectively measured. The liquid from the condenser 3 is divided into a main liquid path and a motor cooling path, on the main liquid path, the liquid refrigerant enters the flash tank 5 after being throttled by the first-stage electronic expansion valve 4, and the gas from the upper part of the flash tank 5 is used as supplement gas to be mixed with the exhaust gas of the low-pressure stage compressor 1 and then enters the high-pressure stage compressor 2. The liquid from the bottom of the flash tank 5 enters the inlet of the evaporator 7 after being throttled by the secondary electronic expansion valve 6, so as to complete the whole refrigeration cycle, wherein the evaporator 7 is provided with an evaporation pressure sensor 20 for detecting the evaporation pressure Pe.
The motor cooling circuit is connected with the first cooling unit and the second cooling unit to cool the motor in the compressor.
The invention also provides a refrigerating device which is a two-stage compression water chilling unit and comprises an evaporator 7, a compressor, a condenser 3, a flash tank 5, a first-stage electronic expansion valve 4 arranged between the condenser 3 and the flash tank 5, a second-stage electronic expansion valve 6 arranged between the flash tank 5 and the evaporator 7 and the cooling system arranged between the condenser 3 and the compressor, wherein the evaporator 7, the compressor, the condenser 3 and the flash tank are sequentially connected through pipelines, and a liquid refrigerant at the bottom of the condenser 3 is used for cooling a motor in the compressor
Specifically, the compressor is a two-stage compressor, including a low-pressure stage compressor 1 and a high-pressure stage compressor 2.
The invention also provides a cooling method for cooling the refrigeration equipment, wherein the refrigeration equipment is a two-stage compression water chilling unit, and the cooling method specifically comprises the following steps:
step 100, starting refrigeration equipment to carry out conventional refrigeration;
step 200, controlling a first cooling unit and/or a second cooling unit to start to cool a motor in a compressor according to the running state of the refrigeration equipment;
and step 300, controlling the cooled liquid to flow back to the evaporator or the flash tank according to the running state of the refrigeration equipment.
In step 200, the operation state of the refrigeration equipment includes that the compressor is in a high pressure ratio operation state, the compressor is in a low pressure ratio operation state, a motor in the compressor is in an overheat state, and a motor in the compressor is in a condensation state.
When only one compressor in the two-stage compressor operates, one branch in the three branches between the electronic expansion valve and the compressor is in a communicated state; when two compressors in the two-stage compressor run and are in a low-pressure ratio running state, two branches in the three branches between the electronic expansion valve and the compressors are in a communicated state; when two compressors in the two-stage compressor are both in operation and in a high pressure ratio operation state, all three branches are in a communication state.
Specifically, for one path of cooling of the automatically-adjusted motor, an electronic expansion valve is adopted in the main path and is connected with a second throttle orifice plate in series, the opening of the electronic expansion valve is adjustable, the second throttle orifice plate is fixedly throttled, three paths of electromagnetic valves are connected in parallel to form a first electromagnetic valve 14, a second electromagnetic valve 15 and a third electromagnetic valve 16 respectively, when only one compressor in the system is detected to be opened, only the second electromagnetic valve 15 or the third electromagnetic valve 16 needs to be opened, meanwhile, when the pressure ratio epsilon is larger than 1.5, a fifth electromagnetic valve 11 of one path from refrigerant return air to the evaporator 7 is opened, and a fourth electromagnetic valve 10 of one path from the backflash generator 5 is closed. On the contrary, when the pressure ratio is less than 1.5, the fourth electromagnetic valve 10 of the refrigerant return air to the flash tank 5 is opened, and the fifth electromagnetic valve 11 is closed; when two compressors are detected in the system, the second electromagnetic valve 15 and the third electromagnetic valve 16 are both opened to cool the motors of the two compressors respectively, the first electromagnetic valve 14 is closed, and meanwhile, when the pressure ratio epsilon is larger than 1.5, the first electromagnetic valve 14 is opened to finish three-way cooling of the motors of the compressors, the fifth electromagnetic valve 11 of one way from refrigerant return air to the evaporator 7 is opened, and the fourth electromagnetic valve 10 of one way from the flash-back generator 5 is closed. On the contrary, when the pressure ratio is less than 1.5, the first electromagnetic valve 14 is closed, the fourth electromagnetic valve 10 of the refrigerant return air to the flash tank 5 is opened, and the fifth electromagnetic valve 11 is closed;
when the compressor is in a high pressure ratio operation state, the cooled liquid flows back to the evaporator; when the compressor is in a low pressure ratio operating state, the cooled liquid flows back to the flash tank.
The high pressure ratio operation state of the compressor means that the pressure ratio epsilon of the compressor is more than or equal to 1.5, and the low pressure ratio operation state of the compressor means that epsilon is less than 1.5. The pressure ratio epsilon of the compressor is equal to the condensation pressure Pc/evaporation pressure Pe;
in step 200, the first cooling unit is in a manual adjustment mode, refrigerant flow rate adjustment is performed by manually adjusting the opening degree of a manually controllable ball valve in the first cooling unit, and the opening degree range of the manually controllable ball valve is 0-100%.
In step 200, the second cooling unit is in an automatic adjustment mode, and comprises the following adjustment steps:
step A: in the shutdown state of the refrigeration equipment, the target opening degree of the electronic expansion valve in the second cooling unit is 0 percent;
and B: starting the refrigeration equipment, and automatically adjusting the opening of the electronic expansion valve to 50% for 3 min;
and C: the electronic expansion valve enters an automatic adjusting mode and is adjusted according to parameters of motor winding temperature difference delta Tj, pressure ratio epsilon, supercooling degree delta Tsc, exhaust superheat degree delta Td and condenser end temperature difference delta Tc;
step D: when the pressure ratio epsilon is more than or equal to 1.5, the minimum value of the target opening of the electronic expansion valve is 0 percent, and the maximum value of the target opening is 100 percent; when the pressure ratio epsilon is less than 1.5, the minimum value of the target opening degree of the electronic expansion valve is 0%, the maximum value of the target opening degree is 50%, the electronic expansion valve is controlled to execute an action every 5s by utilizing the parameters of the supercooling degree delta Tsc, the temperature difference delta Tc of the condenser end and the exhaust superheat degree delta Td, the action amplitude does not exceed 3% every time, and the calculation formula of the action amplitude is as follows: D-D1 + D2+ D3+ D4;
when D is larger than 0.5, the target opening degree of the electronic expansion valve is increased by D%;
when D is more than or equal to 0.5 and more than or equal to-0.5, the target opening of the electronic expansion valve is kept unchanged;
when D < -0.5, the target opening degree of the electronic expansion valve is reduced by D%;
step E: the refrigerating equipment is stopped, and the target opening degree of the electronic expansion valve is changed from the current opening degree to 0%.
The calculation formula of D1, D2, D3 and D4 in the action amplitude is as follows:
when the winding temperature difference delta Tj of the motor is more than or equal to 4 ℃, D1 is 0.6 (delta Tsc-4);
when the motor winding temperature difference delta Tj is less than 4 ℃, D1 is 0.2 (delta Tsc-4);
when the supercooling degree delta Tsc is more than or equal to 2.5 ℃, D2 is 0.3 (delta Tsc-2.5);
when the degree of supercooling Δ Tsc is <2.5 ℃, D2 is 0.8 ═ 2.5 (Δ Tsc-2.5);
when the temperature difference delta Tc at the end of the condenser is less than or equal to 1 ℃, D3 is 0;
when the condenser end temperature difference Δ Tc >1 ℃, D3 is 0.5 ═ Δ Tc-1;
when the exhaust superheat degree delta Td is more than or equal to 3.5 ℃, D4 is 0.3 (delta Td-3.5);
when the exhaust superheat degree Δ Td is less than 3.5 ℃, D4 is 0.9 × (Δ Td-3.5).
The cooling system provided by the invention is applied to a two-stage compression water chilling unit, and two sets of cooling units can be selected to participate in cooling of the compressor motor or all the cooling units participate in cooling of the motor, so that sufficient and reasonable cooling of the motor under different working conditions in the two-stage compression water chilling unit system is guaranteed; the shutdown caused by burning out of the motor winding is avoided, the condensation caused by supercooling of the motor is avoided, and the long-term stable operation of the unit is ensured; by arranging the two backflow units in parallel, the cooling liquid is controlled to flow back into the evaporator or the flash evaporator under different running states of the equipment, so that the reasonable cooling of the motor is guaranteed, and meanwhile, the uncertainty that refrigerants enter the evaporator or the flash evaporator under different working conditions is avoided.
Example 1:
the cooling system provided by the invention solves the problem that the motor is not fully cooled and damaged under the working condition that the compressor pressure is higher in a two-stage compression system, and also solves the problem that the motor cannot generate supercooling to waste the unit cold energy, reduce the unit performance or cause the motor to be condensed under the working condition that the compressor pressure is lower; the problem of refrigerant absorb low, high-pressure stage compressor's motor heat after get into the uncertainty of evaporimeter or flash tank is solved, under the great operating mode of pressure ratio promptly, control refrigerant return-air gets into the evaporimeter, and under the less operating mode of pressure ratio, control refrigerant return-air gets into the flash tank, avoids refrigerant return-air fixed entering evaporimeter or fixed entering flash tank to cause the waste or the refrigerated not enough of cold volume under the different operating modes.
The cooling system provided by the invention is a cooling system with two paths of motor cooling and air return: the two cooling paths are respectively manual cooling adjustment and real-time automatic cooling adjustment, the two paths are parallelly connected and opened to realize simultaneous adjustment, when the motor is overheated or condensed, the opening of the manual controllable ball valve is manually adjusted, and the refrigerant circulation of the cooling motor can be manually and reasonably controlled. Matching the operation working conditions of different compressor heating values, and adopting a mode that a manual adjustable ball valve is connected with a fixed first throttle orifice plate in series for one path of manual cooling adjustment; the other path of automatic cooling adjustment adopts a second throttle orifice plate to be connected with an electronic expansion valve in series, and then the automatic cooling adjustment is divided into three paths, and each of the three paths is provided with an electromagnetic valve; after the gaseous refrigerant after heat exchange with the motor comes out, the return air is divided into two paths, one path returns to the flash evaporator, the other path returns to the evaporator, and the two paths are respectively provided with an electromagnetic valve.
The automatic cooling and air return control method of the cooling system comprises the steps of measuring evaporation and condensation pressures through the pressure sensor to calculate the pressure ratio, measuring other operation parameters of the unit through the temperature sensor, controlling the opening of the electronic expansion valve on the automatic adjusting circuit and the opening and closing of some electromagnetic valves in the unit by matching with control logic, and accurately controlling the winding temperature of the motor, thereby ensuring the reasonable cooling and air return of the motor in the unit and ensuring the safe and stable operation of the motor and the unit
The parameters used for the automatic adjustment mode are:
the motor winding temperature difference delta Tj is equal to a motor winding temperature-motor winding temperature set value;
pressure ratio epsilon is condensation pressure Pc/evaporation pressure Pe;
the supercooling degree delta Tsc is equal to the condensation temperature Tc-the condenser liquid outlet temperature Tsc;
the exhaust superheat degree delta Td is equal to the exhaust temperature Td-condensation temperature Tc;
the temperature difference delta Tc of the condenser end is equal to the condensation temperature Tc-the cooling water outlet temperature Tco;
it should be noted that "inward" is a direction toward the center of the accommodating space, and "outward" is a direction away from the center of the accommodating space.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in fig. 1 to facilitate the description of the invention and to simplify the description, but are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (19)
1. A cooling system is characterized by comprising a first cooling unit and a second cooling unit which are arranged between a condenser and a compressor in parallel, wherein the first cooling unit and the second cooling unit refrigerate in a partial operation mode or a full operation mode.
2. The cooling system of claim 1, wherein the first cooling unit is in a manual adjustment mode and the second cooling unit is in an automatic adjustment mode.
3. The cooling system of claim 2, wherein the first cooling unit comprises a manually controllable ball valve and a first orifice plate connected by a conduit.
4. The cooling system of claim 2, wherein the second cooling unit comprises a second orifice plate and an electronic expansion valve connected by piping.
5. The cooling system of claim 4, wherein the compressor is a two-stage compressor comprising a low-pressure stage compressor and a high-pressure stage compressor, and the first cooling unit and the second cooling unit are both connected to the two-stage compressor; the outlet side of the electronic expansion valve is also provided with three branches in parallel, and each branch is provided with an electromagnetic valve; wherein two of the branches are connected to the high pressure stage compressor and one of the branches is connected to the low pressure stage compressor.
6. The cooling system according to any one of claims 1 to 5, further comprising a reflux unit, wherein the reflux unit comprises a first reflux unit and a second reflux unit which are arranged in parallel, and two ends of the first reflux unit are respectively connected with the compressor and the flash tank; and two ends of the second backflow unit are respectively connected with the compressor and the evaporator.
7. The cooling system according to claim 6, wherein solenoid valves are provided on both the first and second return units.
8. The cooling system according to claim 5, further comprising a detection element including a motor winding temperature sensor provided on the compressor, an exhaust gas temperature sensor provided on an outlet side of the high-pressure stage compressor, a condensing pressure sensor provided on the condenser, a cooling water outlet water temperature sensor and a condenser outlet water temperature sensor, an evaporation pressure sensor provided on an evaporator.
9. Refrigeration device, comprising an evaporator, a compressor, a condenser, a flash tank, a primary electronic expansion valve arranged between the condenser and the flash tank, a secondary electronic expansion valve arranged between the flash tank and the evaporator, and a cooling system according to any one of claims 1 to 8 arranged between the condenser and the compressor, in series, in pipe connection.
10. The refrigeration apparatus of claim 9 wherein the compressor is a two-stage compressor comprising a low pressure stage compressor and a high pressure stage compressor.
11. The refrigeration appliance according to claim 9 wherein the refrigeration appliance is a two-stage compression chiller.
12. A cooling method for cooling the refrigerating apparatus as claimed in any one of claims 9 to 11, comprising the steps of:
step 100, starting refrigeration equipment to carry out conventional refrigeration;
step 200, controlling a first cooling unit and/or a second cooling unit to start to cool a motor in a compressor according to the running state of the refrigeration equipment;
and step 300, controlling the cooled liquid to flow back to the evaporator or the flash tank according to the running state of the refrigeration equipment.
13. The cooling method as claimed in claim 12, wherein the operation state of the refrigerating apparatus in step 200 includes a high pressure ratio operation state of the compressor, a low pressure ratio operation state of the compressor, an overheat state of the motor in the compressor, and a dew condensation state of the motor in the compressor.
14. The cooling method as claimed in claim 13, wherein when only one of the two-stage compressors is operated, one of three branches between the electronic expansion valve and the compressor is in a communicating state; when two compressors in the two-stage compressor run and are in a low-pressure ratio running state, two branches in the three branches between the electronic expansion valve and the compressors are in a communicated state; when two compressors in the two-stage compressor are both in operation and in a high pressure ratio operation state, all three branches are in a communication state.
15. The cooling method according to claim 13, wherein the cooled liquid is returned to the evaporator when the compressor is in a high pressure ratio operation state; when the compressor is in a low pressure ratio operating state, the cooled liquid flows back to the flash tank.
16. The cooling method as set forth in claim 13, wherein the high pressure ratio operation state of the compressor is when a pressure ratio e of the compressor is equal to or greater than 1.5, and the low pressure ratio operation state of the compressor is when e < 1.5.
17. The cooling method according to claim 12, wherein in the step 200, the first cooling unit is in a manual adjustment mode, and the refrigerant flow rate is adjusted by manually adjusting an opening degree of a manually controllable ball valve in the first cooling unit, wherein the opening degree of the manually controllable ball valve is in a range of 0% to 100%.
18. The cooling method according to claim 12, wherein in step 200, the second cooling unit is in an automatic adjustment mode, comprising the adjustment steps of:
step A: in the shutdown state of the refrigeration equipment, the target opening degree of the electronic expansion valve in the second cooling unit is 0 percent;
and B: starting the refrigeration equipment, and automatically adjusting the opening of the electronic expansion valve to 50% for 3 min;
and C: the electronic expansion valve enters an automatic adjusting mode and is adjusted according to parameters of motor winding temperature difference delta Tj, pressure ratio epsilon, supercooling degree delta Tsc, exhaust superheat degree delta Td and condenser end temperature difference delta Tc;
step D: when the pressure ratio epsilon is more than or equal to 1.5, the minimum value of the target opening of the electronic expansion valve is 0 percent, and the maximum value of the target opening is 100 percent; when the pressure ratio epsilon is less than 1.5, the minimum value of the target opening degree of the electronic expansion valve is 0%, the maximum value of the target opening degree is 50%, the electronic expansion valve is controlled to execute an action every 5s by utilizing the parameters of the supercooling degree delta Tsc, the temperature difference delta Tc of the condenser end and the exhaust superheat degree delta Td, the action amplitude does not exceed 3% every time, and the calculation formula of the action amplitude is as follows: D-D1 + D2+ D3+ D4;
when D is larger than 0.5, the target opening degree of the electronic expansion valve is increased by D%;
when D is more than or equal to 0.5 and more than or equal to-0.5, the target opening of the electronic expansion valve is kept unchanged;
when D < -0.5, the target opening degree of the electronic expansion valve is reduced by D%;
step E: the refrigerating equipment is stopped, and the target opening degree of the electronic expansion valve is changed from the current opening degree to 0%.
19. The cooling method according to claim 18, wherein the calculation formula of D1, D2, D3 and D4 in the action amplitude is:
when the winding temperature difference delta Tj of the motor is more than or equal to 4 ℃, D1 is 0.6 (delta Tsc-4);
when the motor winding temperature difference delta Tj is less than 4 ℃, D1 is 0.2 (delta Tsc-4);
when the supercooling degree delta Tsc is more than or equal to 2.5 ℃, D2 is 0.3 (delta Tsc-2.5);
when the degree of supercooling Δ Tsc is <2.5 ℃, D2 is 0.8 ═ 2.5 (Δ Tsc-2.5);
when the temperature difference delta Tc at the end of the condenser is less than or equal to 1 ℃, D3 is 0;
when the condenser end temperature difference Δ Tc >1 ℃, D3 is 0.5 ═ Δ Tc-1;
when the exhaust superheat degree delta Td is more than or equal to 3.5 ℃, D4 is 0.3 (delta Td-3.5);
when the exhaust superheat degree Δ Td is less than 3.5 ℃, D4 is 0.9 × (Δ Td-3.5).
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