CN115493307A - Cooling system, control method and air conditioning unit - Google Patents

Cooling system, control method and air conditioning unit Download PDF

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Publication number
CN115493307A
CN115493307A CN202211340537.3A CN202211340537A CN115493307A CN 115493307 A CN115493307 A CN 115493307A CN 202211340537 A CN202211340537 A CN 202211340537A CN 115493307 A CN115493307 A CN 115493307A
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China
Prior art keywords
flow path
exv1
throttle valve
evaporator
cooling system
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CN202211340537.3A
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Chinese (zh)
Inventor
周宇
黄成武
何子羽
钟瑞兴
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Gree Electric Appliances Inc of Zhuhai
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Gree Electric Appliances Inc of Zhuhai
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Priority to CN202211340537.3A priority Critical patent/CN115493307A/en
Publication of CN115493307A publication Critical patent/CN115493307A/en
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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
    • F25B5/00—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity
    • F25B5/02—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity arranged in parallel
    • 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
    • F25B41/24—Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part
    • 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
    • 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
    • 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
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/19—Pumping down refrigerant from one part of the cycle to another part of the cycle, e.g. when the cycle is changed from cooling to heating, or before a defrost cycle is started
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

The invention discloses a cooling system, a control method and an air conditioning unit, wherein the cooling system comprises: the main loop is provided with a compressor, a condenser, a flash evaporator and an evaporator which are sequentially connected, one end of the cooling branch is connected to the condenser through a cooling throttle valve, the other end of the cooling branch is provided with a flash flow path and an evaporation flow path, the on-off state of the flash flow path and the on-off state of the evaporation flow path can be switched, the flash flow path is connected to the flash evaporator, the evaporation flow path is connected to the evaporator, and the evaporation flow path is provided with a refrigerant pump. According to the invention, the refrigerant pump is additionally arranged on the evaporation flow path, and after the evaporation flow path is communicated, the refrigerant is pressurized by the refrigerant pump, so that the pressure difference between the front end and the rear end of the cooling branch is increased, the cooling capacity is improved, and insufficient cooling is avoided.

Description

Cooling system, control method and air conditioning unit
Technical Field
The invention relates to the technical field of cooling systems, in particular to a cooling system with a condenser and a refrigerant pump jointly supplying liquid, a control method and an air conditioning unit.
Background
For the air conditioning unit, the heat generating components such as the motor generate a large amount of heat as the running time is accumulated during the use, and therefore, an effective cooling scheme is required to ensure the reliability of the operation of the motor. At present, a conventional cooling scheme is that a high-pressure liquid refrigerant is taken from a condenser, cooled and depressurized by an electronic expansion valve, and then the liquid refrigerant is sent to a heating component by using the pressure difference between the condensing pressure of the refrigerant in the condenser and the refrigerant in an evaporator, so that the refrigerant after absorbing heat and evaporating enters the evaporator, thereby achieving the purpose of cooling the heating component. However, due to the different operating conditions of the units, the pressure difference between the condenser and the evaporator varies greatly, and the change of the cooling liquid supply amount before and after the switching of the operating conditions is easily caused by the reduction of the pressure difference, so that the excessive or insufficient cooling liquid supply of the heating components is caused, and the normal operation of the heating components and the units is influenced.
Poor scheme to adaptability around the operating mode switches has appeared among the prior art, and it is through being connected to flash tank and evaporimeter respectively with the cooling branch road, relies on the cooling liquid supply volume that switches the flow path on-off state and adjust the aperture of choke valve and increases or reduce the cooling branch road, avoids cooling surplus or cooling insufficiency. However, the throttle valve has a very limited capacity for adjusting the refrigerant flow rate, and cannot effectively ensure the refrigerant liquid supply amount, and the refrigerant liquid supply amount is still insufficient due to the reduction of the pressure difference during the operation of the unit.
Therefore, how to design a cooling system, a control method and an air conditioning unit for effectively improving cooling capacity is an urgent technical problem to be solved in the industry.
Disclosure of Invention
In order to solve the defects of limited pressure difference adjusting range and insufficient cooling output capacity of the existing air conditioning unit, the invention provides a cooling system, a control method and the air conditioning unit.
The technical scheme adopted by the invention is that a cooling system is designed, and the cooling system comprises: the main loop is provided with a compressor, a condenser, a flash evaporator and an evaporator which are sequentially connected, one end of the cooling branch is connected to the condenser through a cooling throttle valve, the other end of the cooling branch is provided with a flash flow path and an evaporation flow path, the on-off states of the flash flow path and the evaporation flow path can be switched over, the flash flow path is connected to the flash evaporator, the evaporation flow path is connected to the evaporator, and a refrigerant pump is installed in the evaporation flow path.
Further, the cooling system further includes: the first detection module is used for detecting the coolant supply amount of the cooling system, and the coolant pump and the first detection module are connected to a controller of the cooling system; when the evaporation flow path is connected, the controller starts the refrigerant pump and controls the working state of the refrigerant pump according to the refrigerant liquid supply quantity.
In some embodiments, the first detection module employs a liquid level sensor mounted in the condenser or evaporator or a flow meter mounted on the cooling branch or main circuit.
Furthermore, the main loop is provided with a primary throttle valve and a secondary throttle valve, the primary throttle valve is connected between the condenser and the flash evaporator in series, and the secondary throttle valve is connected between the flash evaporator and the evaporator in series.
Further, the cooling system further includes: the second detection module is used for detecting the temperature parameters of the main loop and the cooling branch, the primary throttle valve, the secondary throttle valve and the second detection module are all connected to the controller of the cooling system, and the controller synchronously adjusts the opening degrees of the primary throttle valve and the secondary throttle valve according to the temperature parameters.
Further, the temperature parameters include: the actual temperature of the heat generating components, the temperature of the refrigerant before and after flowing through the heat generating components, the evaporation temperature of the evaporator, and the temperature of the chilled water leaving the evaporator.
The invention also provides a control method of the cooling system, which comprises the following steps:
detecting an actual temperature of the heat generating component;
switching the on-off state of the flash flow path and the evaporation flow path according to the actual temperature;
and after the evaporation flow path is connected, controlling the working state of the refrigerant pump according to the refrigerant liquid supply quantity of the cooling system.
Further, controlling the working state of the refrigerant pump according to the refrigerant supply amount includes:
when the refrigerant liquid supply amount reaches above the set liquid supply amount, maintaining the current opening of the refrigerant pump;
and when the liquid supply amount of the refrigerant is lower than the set liquid supply amount, increasing the opening of the refrigerant pump.
In some embodiments, the coolant supply amount is an actual liquid level of the condenser, and the set liquid supply amount is a set liquid level of the condenser; the opening degree of the refrigerant pump after being increased is obtained by calculation through a set function model, wherein the set function model is as follows: opening = (actual liquid level × 0.3 × rated flow)/100.
Further, switching the on-off state of the flash flow path and the evaporation flow path according to the actual temperature includes:
when the actual temperature is lower than a set lower limit threshold, the flash flow path is switched on, and the evaporation flow path is closed;
and when the actual temperature is higher than the set upper limit threshold value, closing the flash flow path and connecting the evaporation flow path.
Further, the control method further comprises: when the actual temperature is within the target temperature range, the opening degree of the first-stage throttle valve and the opening degree of the second-stage throttle valve are kept unchanged;
and when the actual temperature is out of the target temperature range, detecting the temperature parameters of the main loop and the cooling branch, and synchronously adjusting the opening of the primary throttle valve and the opening of the secondary throttle valve according to the temperature parameters.
In some embodiments, synchronously adjusting the opening of the first-stage throttle valve and the opening of the second-stage throttle valve based on the temperature parameter comprises:
D＝D1+D2，D C ＝U×D；
d1=0 when |. Tshdt |, is less than or equal to the set deviation;
d1= a _ EXV1 × Kp _ EXV1 ×. Δ Tshdt + a _ EXV1 × Ki _ EXV1 × (. Δ Tshdt-. Δ Tshdt'),. Δ Tshdt = Tshd-Tshdt when | > sets the deviation;
d2= A _ EXV1 × Kp1_ EXV1 × DeltaTdwct, deltaTdwct = Tdwc-A _ EXV1 × dwc _ EXV1 when Tdwc ≧ A _ EXV1 × dwc _ EXV1;
d2=0 when Tdwc < a _ EXV1 × dwc _ EXV1;
wherein D is the opening regulating quantity of the first-stage throttle valve, and D C The opening degree regulating quantity of the two-stage throttle valve is U, tshd, tshdt, A _ EXV1, kp1_ EXV1, ki _ EXV1, tdwc, dwc _ EXV1, tdwct and Tdwct respectively, is a proportional coefficient, tshd is the actual overheating degree of a heating component, tshdt is the target overheating degree of the heating component, tshdt is the overheating degree of the heating component in the current period, A _ EXV1 is a correction coefficient, kp _ EXV1 and Kp1_ EXV1 are both proportional coefficients, ki _ EXV1 is an integral coefficient, tdwc is the actual temperature difference of an evaporator end, dwc _ EXV1 is the target temperature difference of an evaporator end, and Tdwct is the temperature difference of the evaporator end.
The invention also provides an air conditioning unit which adopts the cooling system.
In some embodiments, the air conditioning unit is a centrifugal chiller.
Compared with the prior art, the invention has the following beneficial effects:
1. by additionally arranging the refrigerant pump on the evaporation flow path, after the evaporation flow path is communicated, the refrigerant is pressurized by the refrigerant pump, so that the pressure difference between the front end and the rear end of the cooling branch is increased, the liquid supply amount of the refrigerant is ensured, the cooling capacity is effectively improved, and insufficient cooling is avoided;
2. the controller synchronously adjusts the opening of the first-stage throttle valve and the second-stage throttle valve according to the temperature parameters so as to reasonably match the cooling capacity of the cooling system with the heat productivity of the heating component, avoid the cold loss of the cooling system and improve the operation reliability of the air conditioning unit.
Drawings
The invention is described in detail below with reference to examples and figures, in which:
FIG. 1 is a schematic diagram of the connections of the cooling system of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the patent and do not limit the patent.
As shown in fig. 1, the cooling system of the present invention is suitable for use in air conditioning units, including but not limited to centrifugal chiller units. The cooling system mainly comprises a main circuit with a compressor 5, a condenser 1, a flash tank 8 and an evaporator 13 connected in series, and a cooling branch circuit for cooling a heat generating component 6, one end of which is connected to the condenser 1 through a cooling throttle valve 3, and the other end of which is connected to the low pressure side of the cooling system. In more detail, a part of refrigerant flowing out of the condenser 1 is sent to a cooling branch, the other end of the cooling branch is provided with a flash flow path and an evaporation flow path in parallel, the flash flow path is connected to a flash unit 8, an air outlet of the flash unit 8 is connected to an air supplement port of the compressor 5 through an intermediate air supplement pipeline 2, an air outlet of the flash unit 8 is connected to an evaporator 13, the evaporation flow path is connected to the evaporator 13, the flash flow path is provided with a flash control valve 7, the evaporation flow path is provided with an evaporation control valve 9, the on-off state of the flow path where the flash unit is located can be flexibly switched through the flash control valve 7 and the evaporation control valve 9, and the refrigerant flowing out of the cooling branch can be sent to the flash unit 8 through the flash flow path or sent to the evaporator 13 through the evaporation flow path.
The heat generating components include, but are not limited to, an electric motor, for example, a cooling system is designed according to the following principle: according to the fluid mechanics principle and related research experience, the mass flow of the fluid flowing through a throttle valve is calculated according to the following formula:
Figure BDA0003915267420000041
wherein, C D For the flow coefficient, A is the flow area of the throttle valve, and they are all only related to the geometry of the throttle valve; delta p is the differential pressure before and after the throttle valve; ρ is a unit of a gradient 1 Is the pre-throttle fluid density.
According to the flow formula, neglecting the flow loss of the refrigerant in the motor or the evaporator, and under the condition of throttle valve type selection determination (geometric structure determination), C D And A is a definite value, Δ p is the condensation pressure p c With evaporation pressure p e (Cooling branch to steamHair bulb) or condensation pressure p c And flash pressure p s (cooling branch to flash vessel) difference, p 1 The density of the refrigerant liquid at the front end of the cooling branch, namely the outlet of the condenser; the outlet conditions of the condenser 1 are the same for the same design conditions, i.e. p 1 The same is true. Therefore, under the same other conditions, the pressure difference Δ p between the cooling branch and the evaporator 13 is larger than that between the cooling branch and the flash tank 8, and the refrigerant flow rate of the cooling branch is larger.
Under certain working conditions that the condensing and evaporating pressure difference is large, the refrigeration cycle efficiency is poor, and in order to ensure the large output capacity of the unit, the power of the motor is large, so that the heat productivity of the motor is larger than that of the conventional working conditions. In order to ensure the cooling reliability, a throttle valve is designed by the maximum heating value of the cooling system, if the cooling pipeline is singly connected to the evaporator 13 or the flash evaporator 8, the adjusting range of the throttle valve is only limited in the operating range under the large-load working condition, the small-load operating range under the refrigeration working condition deviates from the large-load working condition, the heating value of the motor is much smaller, the cooling capacity of the cooling system is excessive, and the cooling capacity loss of the system is caused; if design the choke valve according to, then can't satisfy required cooling capacity under the heavy load operating mode, the motor can be overheated, influences life.
Based on the above analysis, the flash flow path and the evaporation flow path are designed at the outlet of the cooling branch, and the on-off state of the flash flow path and the evaporation flow path is switched according to the heat generation amount of the heat generating component, so as to adjust the amount of the refrigerant liquid supply to adapt to the heat generation condition of the heat generating component. According to the invention, on the basis of the flash flow path and the evaporation flow path, the refrigerant pump is arranged on the evaporation flow path, when the temperature of a heating component is higher, the evaporation flow path is communicated, the refrigerant pump 10 is started to work, and the refrigerant flows out of the condenser 1 and is pressurized by the refrigerant pump 10, so that the pressure difference of an inlet and an outlet of the cooling branch is increased, thereby ensuring the liquid supply amount of the refrigerant, effectively improving the cooling capacity and avoiding insufficient cooling.
As shown in fig. 1, in some embodiments, the cooling system further comprises: the liquid level sensor 11 and the liquid level sensor 11 are used for detecting the actual liquid level of the condenser 1, and the actual liquid level accurately reflects the amount of the refrigerant liquid supply of the cooling system. In order to realize the automatic control of the refrigerant pump, the refrigerant pump 10 and the liquid level sensor 11 are both connected to a controller of the cooling system, when the evaporation flow path is connected, the controller starts the refrigerant pump 10 and controls the working state of the refrigerant pump 10 according to the actual liquid level, namely when the actual liquid level is lower, the opening degree of the refrigerant pump 10 is increased, and the refrigerant liquid supply amount is increased.
It should be understood that the refrigerant supply amount of the cooling system is detected by the first detection module, the liquid level sensor is only a possible implementation of the first detection module, and the first detection module may also adopt a flow meter, and the flow rate of the refrigerant of the cooling branch detected by the flow meter reflects the amount of the refrigerant supply amount of the cooling system. In practical application, the liquid level sensor can also detect the liquid level of the evaporator to reflect the refrigerant liquid supply amount of the cooling system, and the flow meter can also reflect the refrigerant liquid supply amount of the cooling system when detecting the refrigerant flow of the main loop.
In some embodiments, the main circuit is provided with a primary throttle 4 and a secondary throttle 12, the primary throttle 4 being connected in series between the condenser 1 and the flash evaporator 8, the secondary throttle 12 being connected in series between the flash evaporator 8 and the evaporator 13, the cooling flow being regulated by the primary throttle 4 and the secondary throttle 12. In order to realize the automatic control of the first-stage throttle valve 4 and the second-stage throttle valve 12, the first-stage throttle valve 4 and the second-stage throttle valve 12 are both connected to a controller of the cooling system, the cooling system is further provided with a second detection module, the second detection module is used for detecting temperature parameters of a main loop and a cooling branch, and the controller synchronously adjusts the opening degrees of the first-stage throttle valve 4 and the second-stage throttle valve 12 according to the temperature parameters.
More specifically, the second detection module includes a plurality of temperature sensors, which are respectively used to detect the actual temperature of the heat generating component, the temperatures of the refrigerant before and after flowing through the heat generating component, the evaporation temperature of the evaporator, and the temperature of the chilled water flowing out of the evaporator, the second detection module collects the temperature of the refrigerant before the cooling branch passes through the heat generating component and the temperature of the refrigerant after passing through the heat generating component, the controller obtains the superheat degree of the actual temperature of the heat generating component from the temperature difference between the temperatures of the refrigerant before and after passing through the heat generating component 6, and a part of the adjustment amount of the primary throttle valve 4 is calculated by using the superheat degree of the actual temperature of the heat generating component. The second detection module also collects the evaporating temperature of the evaporator 13 and the outlet water temperature of the chilled water flowing out of the evaporator 13, the controller obtains the actual evaporator end temperature difference by taking the temperature difference between the outlet water temperature of the chilled water and the evaporating temperature, the other part of regulating quantity of the primary throttle valve 4 is calculated by utilizing the actual evaporator end temperature difference, the two parts of regulating quantity are superposed to obtain the opening regulating quantity of the primary throttle valve 4, the opening of the secondary throttle valve 12 is synchronously regulated along with the primary throttle valve 4, the output capacity of the cooling system can be reasonably matched with the heating quantity of the heating component 6 and the load demand of the terminal equipment by regulating the openings of the primary throttle valve 4 and the secondary throttle valve 12, the running stability of the unit is improved, and insufficient or waste of cooling capacity is avoided.
Specifically, the controller executes the following control method:
detecting the actual temperature of the heat generating component 6;
switching the on-off states of the flash flow path and the evaporation flow path according to the actual temperature, switching on the flash flow path and closing the evaporation flow path when the actual temperature is lower than a set lower limit threshold, and switching off the flash flow path and switching on the evaporation flow path when the actual temperature is higher than a set upper limit threshold;
after the evaporation flow path is connected, the operating state of the refrigerant pump 10 is controlled according to the refrigerant supply amount of the cooling system.
Specifically, the working state adjusting process of the refrigerant pump 10 is as follows: work is setting for initial aperture when refrigerant pump 10 starts, when the refrigerant supplies the liquid measure to reach when setting for more than the liquid measure, explains cooling system's refrigerant supplies the liquid measure sufficient, and the controller maintains refrigerant pump 10's current aperture, supplies the liquid measure to be less than when setting for when supplying the liquid measure when the refrigerant, explains cooling system's refrigerant supplies the liquid measure not enough, and the controller increases refrigerant pump 10's aperture to the exit differential pressure of increase cooling branch promotes the refrigerant and supplies the liquid measure.
In order to realize accurate control of the opening degree of the refrigerant pump, in some embodiments, the refrigerant liquid supply amount is an actual liquid level of the condenser, and the liquid supply amount is set as a set liquid level of the condenser, the inventor obtains a set function model suitable for the centrifugal chiller through a large number of experimental statistical analyses, the increased opening degree of the refrigerant pump is obtained through calculation of the set function model, and the set function model is: opening degree = (actual liquid level × 0.3 × rated flow rate)/100, and the rated flow rate is a rated flow rate of the refrigerant pump.
In some embodiments, the control method further comprises:
when the actual temperature is within the target temperature range, the temperature of the heating part is within a proper range, the cooling capacity of the cooling system is properly supplied, and the opening degree of the first-stage throttle valve and the opening degree of the second-stage throttle valve are kept unchanged;
when the actual temperature is outside the target temperature range, the temperature of the heating component is over high or over low, the cold quantity supply of the cooling system is insufficient or over-supplied, the temperature parameters of the main loop and the cooling branch are detected, and the opening of the primary throttle valve and the opening of the secondary throttle valve are synchronously adjusted according to the temperature parameters.
It should be noted that the upper threshold and the lower threshold are designed according to the heat resistance of the heat generating component, and in the case of a motor, the upper threshold may be designed to be 58 ℃ and the lower threshold may be designed to be 32 ℃. The target temperature interval is a target temperature +/-margin, the margin can be designed to be 4 ℃ and the like, and the target temperature interval is between a set upper limit threshold and a set lower limit threshold. The set liquid level is the liquid level of the unit in the optimal operation state as the design standard, and the optimal liquid level of 1/2 or other proportion is taken as the set liquid level according to the actual use requirement.
In some embodiments, the opening of the first-stage throttle valve and the opening of the second-stage throttle valve are adjusted as follows:
D＝D1+D2，D C ＝U×D；
when |. Tshdt | ≦ the set deviation, it indicates that the temperature of the heat generating component is effectively controlled, D1=0;
when Δ Tshdt > is a set deviation, it means that the cooling capacity supply deviation of the cooling branch is large, the throttle valve needs to be adjusted to adapt to the heat generation amount of the heat generating component 6, and D1= a _ EXV1 × Kp _ EXV1 × Tshdt + a _ EXV1 × Ki _ EXV1 is used as a reference
(△Tshdt-△Tshdt’)，△Tshdt＝Tshd－Tshdt；
When Tdwc is more than or equal to A _ EXV1 × dwc _ EXV1, which indicates that the cold supply deviation of the evaporator is large, the throttle valve needs to be adjusted to adapt to the load demand of the end equipment, D2= A _ EXV1 × Kp1_ EXV1 × DeltaTwct, deltaTwct = Tdwc-A _ EXV1 × dwc _ EXV1;
when Tdwc < a _ EXV1 × dwc _ EXV1, indicating that the refrigeration supply of the evaporator is appropriate, D2=0;
wherein D is the opening regulating quantity of the first-stage throttle valve, and D C The opening adjustment amount of the two-stage throttle valve is U, tshd, tshdt, a calculation formula of the target heating component humidity superheat degree, and can be obtained by fitting experimental data, or the target heating component temperature superheat degree is designed to be a fixed value to simplify control logic, wherein the Tshdt is the heating component superheat degree deviation in the current period, the Tshdt' is the heating component superheat degree deviation in the previous period, A _ EXV1 is a correction coefficient, kp _ EXV1 and Kp1_ EXV1 are proportional coefficients, ki _ EXV1 is an integral coefficient, tdwc is the actual evaporator end temperature difference, dwc _ EXV1 is the target evaporator end temperature difference, and the Tdwct is the evaporator end temperature difference. In some embodiments, the set deviation is 0.1 ℃, and the specific values of the set deviation and the coefficients such as a _ EXV1 can be designed according to specific requirements in practical applications.
It should be understood that the opening, holding, or closing of the primary and secondary throttle valves is determined by the positive or negative of D1+ D2, with D1+ D2>0 the primary throttle valve being open and the secondary throttle valve subsequently being open, D1+ D2<0 the primary throttle valve being closed and the secondary throttle valve subsequently being closed, and D1+ D2=0 the primary and secondary throttle valves being held at current opening. During the adjustment of the first-stage throttle valve 4 and the second-stage throttle valve 12, the throttle minimum-opening operation is maintained when the throttle valve is already at the minimum opening and D1+ D2<0, and the throttle maximum-opening operation is maintained when the throttle valve is already at the maximum opening and D1+ D2> 0.
It is noted that the terminology used above is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise. The "throttle valve" appearing above may be an electronic expansion valve, and the "control valve" may be a solenoid valve.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (14)

1. A cooling system, comprising: the main circuit is provided with a compressor, a condenser, a flash evaporator and an evaporator which are sequentially connected, one end of the cooling branch is connected to the condenser through a cooling throttle valve, the other end of the cooling branch is provided with a flash flow path and an evaporation flow path, the on-off state of the flash flow path and the on-off state of the evaporation flow path can be switched, the flash flow path is connected to the flash evaporator, and the evaporation flow path is connected to the evaporator; the evaporator is characterized in that the evaporation flow path is provided with a refrigerant pump.
2. The cooling system of claim 1, further comprising: the first detection module is used for detecting the coolant supply amount of the cooling system, and the coolant pump and the first detection module are both connected to the controller of the cooling system; when the evaporation flow path is communicated, the controller starts the refrigerant pump and controls the working state of the refrigerant pump according to the refrigerant liquid supply amount.
3. The cooling system according to claim 2, wherein the first detection module employs a liquid level sensor installed in the condenser or the evaporator or a flow meter installed on the cooling branch or the main circuit.
4. The cooling system of claim 1, wherein the primary loop is provided with a primary throttle valve and a secondary throttle valve, the primary throttle valve being in series between the condenser and the flash tank, the secondary throttle valve being in series between the flash tank and the evaporator.
5. The cooling system of claim 4, further comprising: and the controller synchronously adjusts the opening degrees of the primary throttle valve and the secondary throttle valve according to the temperature parameters.
6. The cooling system of claim 5, wherein the temperature parameters comprise: the actual temperature of the heat generating component, the temperature of the refrigerant before and after flowing through the heat generating component, the evaporation temperature of the evaporator, and the temperature of the chilled water outlet flowing out of the evaporator.
7. A control method of a cooling system, which is applied to the cooling system according to any one of claims 1 to 6, characterized by comprising the steps of:
detecting an actual temperature of the heat generating component;
switching the on-off states of the flash flow path and the evaporation flow path according to the actual temperature;
and after the evaporation flow path is communicated, controlling the working state of the refrigerant pump according to the refrigerant liquid supply amount of the cooling system.
8. The control method of claim 7, wherein controlling the operating state of the refrigerant pump according to the amount of the refrigerant supply fluid comprises:
when the refrigerant liquid supply amount reaches a preset liquid supply amount, maintaining the current opening of the refrigerant pump;
and when the refrigerant liquid supply amount is lower than the set liquid supply amount, increasing the opening degree of the refrigerant pump.
9. The control method according to claim 8, wherein the coolant supply amount is an actual liquid level of the condenser, and the set liquid supply amount is a set liquid level of the condenser; the opening degree of the refrigerant pump after being increased is obtained by calculation through a set function model, wherein the set function model is as follows: opening = (actual liquid level × 0.3 × rated flow)/100.
10. The control method according to claim 7, wherein switching the on-off states of the flash flow path and the evaporation flow path according to the magnitude of the actual temperature includes:
when the actual temperature is lower than a set lower limit threshold, the flash flow path is switched on, and the evaporation flow path is closed;
and when the actual temperature is higher than a set upper limit threshold value, closing the flash flow path and switching on the evaporation flow path.
11. The control method according to claim 10, characterized by further comprising:
when the actual temperature is within the target temperature interval, the opening degree of the first-stage throttle valve and the opening degree of the second-stage throttle valve are kept unchanged;
and when the actual temperature is out of the target temperature range, detecting the temperature parameters of the main loop and the cooling branch, and synchronously adjusting the opening of the primary throttle valve and the opening of the secondary throttle valve according to the temperature parameters.
12. The control method of claim 11, wherein synchronously adjusting the opening of the primary throttle valve and the opening of the secondary throttle valve based on the temperature parameter comprises:
D＝D1+D2，D C ＝U×D；
d1=0 when |. DELTA Tshdt | < the predetermined deviation;
d1= a _ EXV1 × Kp _ EXV1 ×. Δ Tshdt + a _ EXV1 × Ki _ EXV1 × (. DELTA.tshdt-. DELTA.tshdt'),. DELTA.tshdt = Tshdt-Tshdt when | _ Tshdt [ - ] sets the deviation;
when Tdwc ≧ a _ EXV1 × dwc _ EXV1, D2= a _ EXV1 × Kp1_ EXV1 × Δ Tdwct, # Tdwct = Tdwc-a _ EXV1 × dwc _ EXV1;
d2=0 when Tdwc < a _ EXV1 × dwc _ EXV1;
wherein D is the opening regulating quantity of the first-stage throttle valve, and D C The opening degree regulating quantity of the two-stage throttle valve is U, tshd, tshdt, A _ EXV1, kp1_ EXV1, ki _ EXV1, tdwc, dwc _ EXV1, tdwct and Tdwct respectively, is a proportional coefficient, tshd is the actual overheating degree of a heating component, tshdt is the target overheating degree of the heating component, tshdt is the overheating degree of the heating component in the current period, A _ EXV1 is a correction coefficient, kp _ EXV1 and Kp1_ EXV1 are both proportional coefficients, ki _ EXV1 is an integral coefficient, tdwc is the actual temperature difference of an evaporator end, dwc _ EXV1 is the target temperature difference of an evaporator end, and Tdwct is the temperature difference of the evaporator end.
13. Air conditioning assembly, characterized in that it employs a cooling system according to any one of claims 1 to 6.
14. The air conditioning assembly of claim 13, wherein the air conditioning assembly is a centrifugal chiller.
CN202211340537.3A 2022-10-28 2022-10-28 Cooling system, control method and air conditioning unit Pending CN115493307A (en)

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