CN112611041A - Air conditioning unit and electronic expansion valve control method - Google Patents

Air conditioning unit and electronic expansion valve control method Download PDF

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Publication number
CN112611041A
CN112611041A CN202011505765.2A CN202011505765A CN112611041A CN 112611041 A CN112611041 A CN 112611041A CN 202011505765 A CN202011505765 A CN 202011505765A CN 112611041 A CN112611041 A CN 112611041A
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temperature
pressure
opening degree
expansion valve
condenser
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CN112611041B (en
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陈见兴
李根源
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Qingdao Hisense Hitachi Air Conditioning System Co Ltd
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Qingdao Hisense Hitachi Air Conditioning System Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F5/00—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater
    • F24F5/0007—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning
    • F24F5/001—Compression cycle type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
    • F24F11/63—Electronic processing
    • F24F11/64—Electronic processing using pre-stored data
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/70—Control systems characterised by their outputs; Constructional details thereof
    • F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
    • F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
    • F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/89—Arrangement or mounting of control or safety devices
    • 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

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
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Abstract

The invention discloses an air conditioning unit and an electronic expansion valve control method, wherein the air conditioning unit comprises a refrigerant circulation loop, a compressor, a condenser, an electronic expansion valve, an evaporator and a controller, and is configured as follows: acquiring a first operation parameter, a second operation parameter, a third operation parameter, evaporator pressure and compressor power in the operation of the air conditioning unit, wherein the first operation parameter is the suction pressure and suction temperature of the compressor, the second operation parameter is the discharge pressure and discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser discharge liquid temperature; determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power; and controlling the opening degree of the electronic expansion valve through the target opening degree, thereby accurately controlling the opening degree of the electronic expansion valve and reducing the hysteresis action or frequent action of the electronic expansion valve.

Description

Air conditioning unit and electronic expansion valve control method
Technical Field
The application relates to the field of air conditioner control, in particular to an air conditioning unit and an electronic expansion valve control method.
Background
The expansion valve is a key part of the air conditioning system, and the adjusting speed and stability of the expansion valve are related to the stability of the air conditioning system and the cooling and heating effects, so that the comfort of a user is indirectly influenced. When the stability of the system is poor, long-term fluctuation occurs, and the service life of the air conditioning unit is further influenced. Therefore, the regulation of the expansion valve is of critical importance in air conditioning systems. Particularly under low temperature conditions, the air conditioning system is sensitive to state changes, the expansion valve needs to be accurately controlled, fluctuation is avoided, and balance is rapidly achieved.
In the prior art, two typical control modes exist in the conventional unit, wherein one mode is based on suction superheat degree control. And measuring and calculating the suction superheat degree of the compressor in real time, comparing the obtained superheat degree with a target superheat degree, and controlling the action of the electronic expansion valve. The control mode of the scheme is simple, but the response of the temperature sensor is lagged compared with that of the pressure sensor, so that the calculated superheat degree is lagged, the action of the electronic expansion valve is lagged, the liquid level of the evaporator fluctuates, and the performance of the unit is influenced. The other is based on liquid level control, and the adjustment is carried out according to the liquid level of an evaporator or a condenser. The liquid level of the evaporator or the condenser is detected in real time, the detected liquid level is compared with the target liquid level, the action of the electronic expansion valve is controlled, and the liquid level detection device is suitable for units with low superheat degree, such as flooded evaporators. The scheme needs to add a liquid level sensor, so that the unit cost is increased; the unit fault caused by the fault of the liquid level sensor is newly added, so that the fault rate of the unit is improved; the liquid level measurement has certain hysteresis and volatility, and then causes the action lag of the electronic expansion valve, so that the electronic expansion valve has periodic frequent actions during control, and the service life of the valve and the unit is influenced.
Therefore, how to accurately control the opening degree of the electronic expansion valve and reduce the action lag and frequent actions of the electronic expansion valve is a technical problem to be solved at present.
Disclosure of Invention
The invention provides an air conditioning unit, which is used for solving the technical problems of action lag and frequent action of an electronic expansion valve in the prior art, and comprises:
a refrigerant circulation loop, which circulates the refrigerant in a loop composed of a compressor, a condenser, an expansion valve and an evaporator;
the compressor is used for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging the high-temperature and high-pressure refrigerant gas to the condenser;
the condenser is used for performing work of releasing heat to cooling water to condense high-temperature and high-pressure refrigerant gas into high-temperature and high-pressure refrigerant liquid and discharging the high-temperature and high-pressure refrigerant liquid to the electronic expansion valve;
the electronic expansion valve is used for adjusting the flow of the refrigerant liquid;
the evaporator is used for evaporating low-temperature low-pressure refrigerant liquid into low-temperature low-pressure refrigerant gas by absorbing heat from chilled water and discharging the low-temperature low-pressure refrigerant gas to the compressor;
a controller configured to:
acquiring a first operating parameter, a second operating parameter, a third operating parameter, evaporator pressure and compressor power in the operation of the air conditioning unit;
determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power;
controlling the opening degree of the electronic expansion valve through the target opening degree;
the first operation parameter is the suction pressure and the suction temperature of the compressor, the second operation parameter is the discharge pressure and the discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser liquid outlet temperature.
In some embodiments, the controller is configured to:
comparing the target opening degree with a target opening degree at the last moment;
if the absolute value of the difference value between the target opening degree and the target opening degree at the previous moment is smaller than a preset value, controlling the opening degree of the electronic expansion valve to keep the target opening degree at the previous moment;
and if the absolute value of the difference value between the target opening degree and the target opening degree at the previous moment is larger than or equal to a preset value, adjusting the opening degree of the electronic expansion valve to the target opening degree.
In some embodiments, the controller is configured to:
determining a theoretical specific enthalpy of induction for the compressor based on the first operating parameter;
determining a theoretical specific enthalpy of discharge for the compressor based on the second look-ahead parameter;
determining the theoretical specific enthalpy of the discharged liquid of the condenser based on the third operating parameter;
determining a refrigerant mass flow based on the compressor power, the theoretical suction specific enthalpy, and the theoretical discharge specific enthalpy;
determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical specific enthalpy of air suction, the theoretical specific enthalpy of liquid outlet of the condenser and the mass flow of the refrigerant;
and determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporation temperature and the condensation temperature, wherein the evaporation temperature is a preset constant, and the condensation temperature is determined based on the condenser pressure and the equivalent condensation temperature corresponding to the evaporation temperature.
In some embodiments, the theoretical specific enthalpy of intake and the theoretical specific enthalpy of exhaust are determined according to the following formulas
h(P,T)＝(p1+p2*x+p3*x^2+p4*x^3+p5*y+p6*y^2)/(1+p7*x+p8*x^2+p9*x^3+p10*y)
Wherein, P is the suction pressure or the discharge pressure, T is the suction temperature or the discharge temperature, P1, P2, P3, P4, P5, P6, P7, P8, P9 and P10 are preset empirical constants, x is the pressure and y is the temperature.
In some embodiments, the theoretical specific enthalpy of the condenser effluent is determined based on the following equation:
h(Pc,T4)＝p1+p2*x+p3*x^2+p4*x^3+p5*x^4+p6*y+p7*y^2+p8*y^3+p9*y^4+p10*y^5；
wherein, PcIs the condenser pressure, T4For the condenser effluent temperature, p1, p2, p3, p4, p5, p6, p7, p8, p9 and p10 are preset empirical constants, x is pressure and y is temperature.
In some embodiments, the refrigerant mass flow rate is determined according to the following equation:
Figure BDA0002844906880000031
wherein q ismFor the refrigerant mass flow, h1 is the theoretical suction specific enthalpy, h2 is the theoretical discharge specific enthalpy, and N is the compressor power.
In some embodiments, the real-time cooling capacity is determined according to the following formula:
Qe＝qm ＊(h1-h4)；
wherein Q iseFor said real-time refrigerating capacity, qmH1 is the theoretical specific enthalpy of suction, h4And (4) theoretical specific enthalpy of the liquid discharged from the condenser.
In some embodiments, the target opening is determined according to the following formula:
K＝(p1+p2*Ln(x)+p3*(Ln(x))^2+p4*(Ln(x))^3+p5*Ln(y)+p6*(Ln(y))^2)/(1+p7*Ln(x)+p8*(Ln(x))^2+p9*Ln(y)+p10*(Ln(y))^2+p11*(Ln(y))^3)；
and K is the target opening degree, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10 and p11 are preset empirical constants, x is the real-time refrigerating capacity, and y is the condensing temperature.
Correspondingly, the invention also provides a control method of the electronic expansion valve, the method is applied to an air conditioning unit comprising a refrigerant circulation loop, a compressor, a condenser, the electronic expansion valve, an evaporator and a controller, and the method comprises the following steps:
acquiring a first operation parameter, a second operation parameter, a third operation parameter, evaporator pressure and compressor power in the operation of the air conditioning unit, wherein the first operation parameter is the suction pressure and suction temperature of the compressor, the second operation parameter is the discharge pressure and discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser discharge liquid temperature;
determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power;
and controlling the opening degree of the electronic expansion valve through the target opening degree.
In some embodiments, the target opening degree of the electronic expansion valve is determined based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power, and specifically:
determining a theoretical specific enthalpy of induction for the compressor based on the first operating parameter;
determining a theoretical specific enthalpy of discharge for the compressor based on the second look-ahead parameter;
determining the theoretical specific enthalpy of the discharged liquid of the condenser based on the third operating parameter;
determining a refrigerant mass flow based on the compressor power, the theoretical suction specific enthalpy, and the theoretical discharge specific enthalpy;
determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical specific enthalpy of air suction, the theoretical specific enthalpy of liquid outlet of the condenser and the mass flow of the refrigerant;
and determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporation temperature and the condensation temperature, wherein the evaporation temperature is a preset constant, and the condensation temperature is determined based on the condenser pressure and the equivalent condensation temperature corresponding to the evaporation temperature.
Compared with the prior art, the method has the following beneficial effects:
the invention discloses an air conditioning unit and an electronic expansion valve control method, wherein the air conditioning unit comprises a refrigerant circulation loop, a compressor, a condenser, an electronic expansion valve, an evaporator and a controller, and is configured as follows: acquiring a first operation parameter, a second operation parameter, a third operation parameter, evaporator pressure and compressor power in the operation of the air conditioning unit, wherein the first operation parameter is the suction pressure and suction temperature of the compressor, the second operation parameter is the discharge pressure and discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser discharge liquid temperature; determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power; and controlling the opening degree of the electronic expansion valve through the target opening degree, thereby accurately controlling the opening degree of the electronic expansion valve and reducing the hysteresis action or frequent action of the electronic expansion valve.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an air conditioning unit according to an embodiment of the present application;
fig. 2 is a flowchart illustrating a method for controlling an electronic expansion valve according to an embodiment of the present disclosure.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application.
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 one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
Fig. 1 is a schematic structural diagram of an air conditioning unit according to the present application, in which the air conditioning unit performs a refrigeration cycle of the air conditioning unit by using a compressor, a condenser, an electronic expansion valve, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the air that has been conditioned and heat-exchanged.
The low-temperature and low-pressure refrigerant gas from the evaporator is changed into a high-temperature and high-pressure refrigerant gas, and the compressed refrigerant gas is discharged. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released into the cooling water through the condensation process.
The electronic expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the electronic expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a cooling effect by heat-exchanging with a material to be cooled using latent heat of evaporation of a refrigerant. In the whole circulation, the cold water unit produces cold water, and then the cold water exchanges heat with indoor air through the tail end of a fan coil and the like.
As described in the background art, in the prior art, the suction superheat degree control causes the action of the electronic expansion valve to lag due to the response lag of the temperature sensor, and the solution based on the liquid level control needs to add a liquid level sensor, which increases the cost, and the liquid level measurement has certain lag and volatility, which further causes the action lag of the electronic expansion valve, so that the electronic expansion valve periodically and frequently acts.
To further describe the solution of the present application, in an example of the present application, the air conditioning unit includes:
a refrigerant circulation loop, which circulates the refrigerant in a loop composed of a compressor, a condenser, an expansion valve and an evaporator;
the compressor is used for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging the high-temperature and high-pressure refrigerant gas to the condenser;
the condenser is used for performing work of releasing heat to cooling water to condense high-temperature and high-pressure refrigerant gas into high-temperature and high-pressure refrigerant liquid and discharging the high-temperature and high-pressure refrigerant liquid to the electronic expansion valve;
the electronic expansion valve is used for adjusting the flow of the refrigerant liquid;
the evaporator is used for evaporating low-temperature low-pressure refrigerant liquid into low-temperature low-pressure refrigerant gas by absorbing heat from chilled water and discharging the low-temperature low-pressure refrigerant gas to the compressor;
a controller configured to:
acquiring a first operating parameter, a second operating parameter, a third operating parameter, evaporator pressure and compressor power in the operation of the air conditioning unit;
determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power;
controlling the opening degree of the electronic expansion valve through the target opening degree;
the first operation parameter is the suction pressure and the suction temperature of the compressor, the second operation parameter is the discharge pressure and the discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser liquid outlet temperature.
In the embodiment of the application, through gathering first operating parameter, second operating parameter, third operating parameter, evaporimeter pressure and compressor power among the air conditioning unit operation process, carry out the analysis to the real-time load of air conditioning unit, confirm the target aperture of the electronic expansion valve of air conditioning unit, the target aperture is the optimum aperture of the electronic expansion valve that each item operating parameter of above-mentioned unit confirmed, carries out real-time regulation to the aperture of electronic expansion valve according to the target aperture, first operating parameter is the suction pressure and the suction temperature of compressor, the second operating parameter is the discharge pressure and the exhaust temperature of compressor, the third operating parameter is condenser pressure and condenser play liquid temperature.
In order to accurately adjust the opening degree of the electronic expansion valve, in some embodiments, the controller is configured to:
comparing the target opening degree with a target opening degree at the last moment;
if the absolute value of the difference value between the target opening degree and the target opening degree at the previous moment is smaller than a preset value, controlling the opening degree of the electronic expansion valve to keep the target opening degree at the previous moment;
and if the absolute value of the difference value between the target opening degree and the target opening degree at the previous moment is larger than or equal to a preset value, adjusting the opening degree of the electronic expansion valve to the target opening degree.
In this embodiment, in order to avoid the occurrence of frequent operations of the electronic expansion valve, after a target opening degree of the electronic expansion valve is obtained, the target opening degree at this time is compared with a target opening degree at a previous time, if an absolute value of a difference between the target opening degree and the target opening degree at the previous time is smaller than a preset value, it is indicated that a difference between the two target opening degrees is not very large, the opening degree of the electronic expansion valve does not need to be adjusted, the opening degree of the electronic expansion valve is controlled to maintain the target opening degree at the previous time, if the absolute value of the difference between the target opening degree and the target opening degree at the previous time is greater than or equal to the preset value, it is indicated that the difference between the two target opening degrees is large, the opening degree of the electronic expansion valve is not adjusted, which may affect the performance of the air conditioning unit, so that the opening degree of the electronic expansion valve needs to, the service life of the electronic expansion valve is prolonged.
To accurately determine the target opening, in some embodiments, the controller is configured to:
determining a theoretical specific enthalpy of induction for the compressor based on the first operating parameter;
determining a theoretical specific enthalpy of discharge for the compressor based on the second look-ahead parameter;
determining the theoretical specific enthalpy of the discharged liquid of the condenser based on the third operating parameter;
determining a refrigerant mass flow based on the compressor power, the theoretical suction specific enthalpy, and the theoretical discharge specific enthalpy;
determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical specific enthalpy of air suction, the theoretical specific enthalpy of liquid outlet of the condenser and the mass flow of the refrigerant;
and determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporation temperature and the condensation temperature, wherein the evaporation temperature is a preset constant, and the condensation temperature is determined based on the condenser pressure and the equivalent condensation temperature corresponding to the evaporation temperature.
In this embodiment, the specific process of determining the target opening degree is as follows: determining the theoretical specific enthalpy of suction of the compressor based on the first operating parameter, determining the theoretical specific enthalpy of exhaust of the compressor based on the second remote parameter, and determining the theoretical specific enthalpy of outlet liquid of the condenser based on the third operating parameter, further determining the mass flow of the refrigerant based on the compressor power, the theoretical suction specific enthalpy and the theoretical exhaust specific enthalpy, determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical suction specific enthalpy, the theoretical condenser liquid outlet specific enthalpy and the mass flow of the refrigerant, and finally determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporating temperature and the condensing temperature, wherein the evaporating temperature is a preset constant, in the process of determining the target opening degree of the electronic expansion valve, the evaporation temperature is maintained at a fixed value, the condensing temperature is determined based on an equivalent condensing temperature corresponding to the condenser pressure and the evaporating temperature.
In order to obtain the theoretical specific enthalpy of intake and the theoretical specific enthalpy of exhaust, in some embodiments, the theoretical specific enthalpy of intake and the theoretical specific enthalpy of exhaust are determined according to the following formulas
h(P,T)＝(p1+p2*x+p3*x^2+p4*x^3+p5*y+p6*y^2)/(1+p7*x+p8*x^2+p9*x^3+p10*y)
Wherein, P is the suction pressure or the discharge pressure, T is the suction temperature or the discharge temperature, P1, P2, P3, P4, P5, P6, P7, P8, P9 and P10 are preset empirical constants, x is the pressure and y is the temperature.
In the present embodiment, when calculating the intake theoretical specific enthalpy, the intake theoretical specific enthalpy is h1(P1, T1), and when calculating the exhaust theoretical specific enthalpy, the exhaust theoretical specific enthalpy is h2(P2, T2).
To determine the condenser liquid theoretical specific enthalpy, in some embodiments, the condenser liquid theoretical specific enthalpy is determined based on the following equation:
h(Pc,T4)＝p1+p2*x+p3*x^2+p4*x^3+p5*x^4+p6*y+p7*y^2+p8*y^3+p9*y^4+p10*y^5；
wherein, PcIs the condenser pressure, T4For the condenser effluent temperature, p1, p2, p3, p4, p5, p6, p7, p8, p9 and p10 are preset empirical constants, x is pressure and y is temperature.
In this example, PcIs the condenser pressure, T4The theoretical specific enthalpy of the outlet liquid of the condenser is h (P) for the outlet liquid temperature of the condenserc,T4)。
In order to obtain the refrigerant mass flow, in a preferred embodiment of the present application, the refrigerant mass flow is determined according to the following formula:
Figure BDA0002844906880000091
wherein q ismFor the refrigerant mass flow, h1 is the theoretical suction specific enthalpy, h2 is the theoretical discharge specific enthalpy, and N is the compressor power.
In this embodiment, qmThe refrigerant mass flow rate is determined by h1, h2, the theoretical specific enthalpy of air suction, h1, the theoretical specific enthalpy of air discharge, h2 and the compressor power Nm。
In order to determine the real-time cooling capacity, in a preferred embodiment of the present application, the real-time cooling capacity is determined according to the following formula:
Qe＝qm＊(h1-h4)；
wherein Q iseFor said real-time refrigerating capacity, qmH1 is the theoretical specific enthalpy of suction, h4And (4) theoretical specific enthalpy of the liquid discharged from the condenser.
In order to determine the target opening degree, in a preferred embodiment of the present application, the target opening degree is determined according to the following formula:
K＝(p1+p2*Ln(x)+p3*(Ln(x))^2+p4*(Ln(x))^3+p5*Ln(y)+p6*(Ln(y))^2)/(1+p7*Ln(x)+p8*(Ln(x))^2+p9*Ln(y)+p10*(Ln(y))^2+p11*(Ln(y))^3)；
and K is the target opening degree, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10 and p11 are preset empirical constants, x is the real-time refrigerating capacity, and y is the condensing temperature.
The invention discloses an air conditioning unit and an electronic expansion valve control method, wherein the air conditioning unit comprises a refrigerant circulation loop, a compressor, a condenser, an electronic expansion valve, an evaporator and a controller, and is configured as follows: acquiring a first operation parameter, a second operation parameter, a third operation parameter, evaporator pressure and compressor power in the operation of the air conditioning unit, wherein the first operation parameter is the suction pressure and suction temperature of the compressor, the second operation parameter is the discharge pressure and discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser discharge liquid temperature; determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power; and controlling the opening degree of the electronic expansion valve through the target opening degree, thereby accurately controlling the opening degree of the electronic expansion valve and reducing the hysteresis action or frequent action of the electronic expansion valve.
In order to further explain the technical idea of the present invention, the present invention further provides a method for controlling an electronic expansion valve, wherein the method is applied to an air conditioning unit comprising a refrigerant circulation loop, a compressor, a condenser, an electronic expansion valve, an evaporator and a controller, and as shown in fig. 2, the method specifically comprises the following steps:
s201, acquiring a first operation parameter, a second operation parameter, a third operation parameter, evaporator pressure and compressor power in the operation of the air conditioning unit, wherein the first operation parameter is suction pressure and suction temperature of the compressor, the second operation parameter is discharge pressure and discharge temperature of the compressor, and the third operation parameter is condenser pressure and condenser outlet liquid temperature.
In this step, a first operation parameter, a second operation parameter, a third operation parameter, an evaporator pressure and a compressor power in the operation of the air conditioning unit are collected, so as to obtain a target opening degree of the electronic expansion valve through the parameters, the first operation parameter is a suction pressure and a suction temperature of the compressor, the second operation parameter is a discharge pressure and a discharge temperature of the compressor, and the third operation parameter is a condenser pressure and a condenser liquid outlet temperature.
And S202, determining the target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power.
In this step, the target opening degree of the electronic expansion valve is determined by the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure, and the compressor power.
And S203, controlling the opening degree of the electronic expansion valve through the target opening degree.
In order to accurately obtain the target opening degree of the electronic expansion valve, in some embodiments, the target opening degree of the electronic expansion valve is determined based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power, specifically:
determining a theoretical specific enthalpy of induction for the compressor based on the first operating parameter;
determining a theoretical specific enthalpy of discharge for the compressor based on the second look-ahead parameter;
determining the theoretical specific enthalpy of the discharged liquid of the condenser based on the third operating parameter;
determining a refrigerant mass flow based on the compressor power, the theoretical suction specific enthalpy, and the theoretical discharge specific enthalpy;
determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical specific enthalpy of air suction, the theoretical specific enthalpy of liquid outlet of the condenser and the mass flow of the refrigerant;
and determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporation temperature and the condensation temperature, wherein the evaporation temperature is a preset constant, and the condensation temperature is determined based on the condenser pressure and the equivalent condensation temperature corresponding to the evaporation temperature.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not necessarily depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims (10)

1. An air conditioning assembly, comprising:
a refrigerant circulation loop, which circulates the refrigerant in a loop composed of a compressor, a condenser, an expansion valve and an evaporator;
the compressor is used for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging the high-temperature and high-pressure refrigerant gas to the condenser;
the condenser is used for performing work of releasing heat to cooling water to condense high-temperature and high-pressure refrigerant gas into high-temperature and high-pressure refrigerant liquid and discharging the high-temperature and high-pressure refrigerant liquid to the electronic expansion valve;
the electronic expansion valve is used for adjusting the flow of the refrigerant liquid;
the evaporator is used for evaporating low-temperature low-pressure refrigerant liquid into low-temperature low-pressure refrigerant gas by absorbing heat from chilled water and discharging the low-temperature low-pressure refrigerant gas to the compressor;
a controller configured to:
acquiring a first operating parameter, a second operating parameter, a third operating parameter, evaporator pressure and compressor power in the operation of the air conditioning unit;
determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power;
controlling the opening degree of the electronic expansion valve through the target opening degree;
the first operation parameter is the suction pressure and the suction temperature of the compressor, the second operation parameter is the discharge pressure and the discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser liquid outlet temperature.
2. The air conditioning assembly as set forth in claim 1, wherein the controller is configured to:
comparing the target opening degree with a target opening degree at the last moment;
if the absolute value of the difference value between the target opening degree and the target opening degree at the previous moment is smaller than a preset value, controlling the opening degree of the electronic expansion valve to keep the target opening degree at the previous moment;
and if the absolute value of the difference value between the target opening degree and the target opening degree at the previous moment is larger than or equal to a preset value, adjusting the opening degree of the electronic expansion valve to the target opening degree.
3. The air conditioning assembly as set forth in claim 1, wherein the controller is configured to:
determining a theoretical specific enthalpy of induction for the compressor based on the first operating parameter;
determining a theoretical specific enthalpy of discharge for the compressor based on the second look-ahead parameter;
determining the theoretical specific enthalpy of the discharged liquid of the condenser based on the third operating parameter;
determining a refrigerant mass flow based on the compressor power, the theoretical suction specific enthalpy, and the theoretical discharge specific enthalpy;
determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical specific enthalpy of air suction, the theoretical specific enthalpy of liquid outlet of the condenser and the mass flow of the refrigerant;
and determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporation temperature and the condensation temperature, wherein the evaporation temperature is a preset constant, and the condensation temperature is determined based on the condenser pressure and the equivalent condensation temperature corresponding to the evaporation temperature.
4. Air conditioning assembly according to claim 2, characterized in that said theoretical specific enthalpy of suction and of discharge are determined according to the following formulae
h(P,T)＝(p1+p2*x+p3*x^2+p4*x^3+p5*y+p6*y^2)/(1+p7*x+p8*x^2+p9*x^3+p10*y)
Wherein, P is the suction pressure or the discharge pressure, T is the suction temperature or the discharge temperature, P1, P2, P3, P4, P5, P6, P7, P8, P9 and P10 are preset empirical constants, x is the pressure and y is the temperature.
5. The air conditioning assembly as set forth in claim 2 wherein said condenser discharge theoretical specific enthalpy is determined based on the formula:
h(Pc,T4)＝p1+p2*x+p3*x^2+p4*x^3+p5*x^4+p6*y+p7*y^2+p8*y^3+p9*y^4+p10*y^5；
wherein, PcIs the condenser pressure, T4For the condenser effluent temperature, p1, p2, p3, p4, p5, p6, p7, p8, p9 and p10 are preset empirical constants, x is pressure and y is temperature.
6. The air conditioning assembly as set forth in claim 2 wherein said refrigerant mass flow rate is determined according to the formula:
Figure FDA0002844906870000021
wherein q ismFor the refrigerant mass flow, h1 is the theoretical suction specific enthalpy, h2 is the theoretical discharge specific enthalpy, and N is the compressor power.
7. The air conditioning assembly as set forth in claim 2, wherein said real-time cooling capacity is determined according to the formula:
Qe＝qm＊(h1-h4)；
wherein Q iseFor said real-time refrigerating capacity, qmH1 is the theoretical specific enthalpy of suction, h4And (4) theoretical specific enthalpy of the liquid discharged from the condenser.
8. The air conditioning assembly as set forth in claim 2 wherein said target opening is determined according to the formula:
K＝(p1+p2*Ln(x)+p3*(Ln(x))^2+p4*(Ln(x))^3+p5*Ln(y)+p6*(Ln(y))^2)/(1+p7*Ln(x)+p8*(Ln(x))^2+p9*Ln(y)+p10*(Ln(y))^2+p11*(Ln(y))^3)；
and K is the target opening degree, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10 and p11 are preset empirical constants, x is the real-time refrigerating capacity, and y is the condensing temperature.
9. A control method of an electronic expansion valve is characterized in that the method is applied to an air conditioning unit comprising a refrigerant circulation loop, a compressor, a condenser, the electronic expansion valve, an evaporator and a controller, and the method comprises the following steps:
acquiring a first operation parameter, a second operation parameter, a third operation parameter, evaporator pressure and compressor power in the operation of the air conditioning unit, wherein the first operation parameter is the suction pressure and suction temperature of the compressor, the second operation parameter is the discharge pressure and discharge temperature of the compressor, and the third operation parameter is the condenser pressure and the condenser discharge liquid temperature;
determining a target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure and the compressor power;
and controlling the opening degree of the electronic expansion valve through the target opening degree.
10. The method of claim 9, wherein determining the target opening degree of the electronic expansion valve based on the first operating parameter, the second operating parameter, the third operating parameter, the evaporator pressure, and the compressor power comprises:
determining a theoretical specific enthalpy of induction for the compressor based on the first operating parameter;
determining a theoretical specific enthalpy of discharge for the compressor based on the second look-ahead parameter;
determining the theoretical specific enthalpy of the discharged liquid of the condenser based on the third operating parameter;
determining a refrigerant mass flow based on the compressor power, the theoretical suction specific enthalpy, and the theoretical discharge specific enthalpy;
determining the real-time refrigerating capacity of the air conditioning unit based on the theoretical specific enthalpy of air suction, the theoretical specific enthalpy of liquid outlet of the condenser and the mass flow of the refrigerant;
and determining the target opening degree of the electronic expansion valve based on the real-time refrigerating capacity, the evaporation temperature and the condensation temperature, wherein the evaporation temperature is a preset constant, and the condensation temperature is determined based on the condenser pressure and the equivalent condensation temperature corresponding to the evaporation temperature.
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