Air conditioner and defrosting control method thereof

Abstract

The application discloses an air conditioner and a defrosting control method thereof. The air conditioner comprises a compressor, a four-way valve, an outdoor heat exchanger, a first throttling device, a flash tank, a second throttling device, an indoor heat exchanger and a gas supplement valve. The air conditioner further comprises a gas supplement pressure detection device for detecting the intermediate pressure at the liquid inlet of the flash tank, and a gas supplement temperature detection device for detecting the intermediate temperature at the liquid inlet of the flash tank. The controller is configured to: in the defrosting mode, query the saturation temperature corresponding to the intermediate pressure, and calculate the temperature difference between the saturation temperature and the intermediate temperature; when the temperature difference is detected to be equal to zero, control the gas supplement valve to open, and calculate the liquid filling time of the refrigerant filling the flash tank; when the cumulative time of the air conditioner running in the defrosting mode is detected to reach the liquid filling time, control the gas supplement valve to close; and when the air conditioner is detected to meet the defrosting end condition, control the gas supplement valve to close and exit the defrosting mode. The application can shorten the defrosting time, so as to ensure the indoor temperature stability and the comfort of the user.

Description

Technical Field

[0001] This invention relates to the field of air conditioner technology, and in particular to an air conditioner and its defrosting control method. Background Technology

[0002] In winter, when outdoor temperatures are low, air conditioners running in heating mode for extended periods are prone to frost buildup on the outdoor unit's evaporator side. This leads to decreased heating efficiency, and as the frost accumulates, it thickens, increasing the outdoor unit's thermal resistance. This reduces the area for outdoor airflow, increases airflow resistance, and consequently reduces air volume, further lowering the outdoor evaporator temperature and impairing heat exchange. Ultimately, this reduces indoor comfort, failing to meet user needs and negatively impacting the user experience. Therefore, timely and effective defrosting is necessary after a period of operation.

[0003] Currently, air conditioners generally use reverse circulation defrosting, which uses the outdoor heat exchanger as a condenser to release heat in order to defrost the outdoor heat exchanger. However, this defrosting mode takes a long time and can easily lead to a drop in indoor temperature, affecting user comfort. Summary of the Invention

[0004] This invention provides an air conditioner and its defrosting control method, which can shorten the defrosting time to ensure stable indoor temperature and user comfort.

[0005] The air conditioner provided in the first embodiment of the present invention includes:

[0006] The refrigerant circulation loop includes a main circulation loop and a make-up gas branch; wherein, the main circulation loop is composed of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling device, a flash evaporator, a second throttling device, and an indoor heat exchanger connected in sequence; the make-up gas branch is located between the flash evaporator and the make-up gas port of the compressor, and the make-up gas branch is equipped with a make-up gas valve;

[0007] A gas replenishment pressure detection device is installed at the liquid inlet of the flash evaporator to detect the intermediate pressure;

[0008] A gas replenishment temperature detection device is installed at the liquid inlet of the flash evaporator to detect the intermediate temperature;

[0009] Controller, used for:

[0010] When the air conditioner is in defrost mode, the intermediate pressure and intermediate temperature are obtained, the first saturation temperature corresponding to the intermediate pressure is queried, and the temperature difference between the first saturation temperature and the intermediate temperature is calculated.

[0011] When the temperature difference is detected to be zero, the gas supply valve is opened, and the charging time for liquid refrigerant to fill the flash evaporator is calculated.

[0012] When the cumulative time the air conditioner has been running in the defrost mode reaches the liquid filling time, the gas replenishment valve is controlled to close.

[0013] When the air conditioner is detected to meet the defrosting end conditions, the gas supply valve is closed and the defrosting mode is exited.

[0014] In the second embodiment of the present invention, the air conditioner wherein calculating the liquid refrigerant filling time of the flash evaporator includes:

[0015] Obtain the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator and the internal volume of the flash evaporator;

[0016] The ratio of the internal volume to the flow rate is calculated to obtain the filling time for the liquid refrigerant to fill the flash evaporator.

[0017] The air conditioner provided in the third embodiment of the present invention further includes: a refrigerant temperature detection device; wherein,

[0018] The refrigerant temperature detection device is installed on the pipeline between the outdoor heat exchanger and the first throttling device, and is used to detect the refrigerant temperature between the outdoor heat exchanger and the first throttling device.

[0019] Then, the controller obtains the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator through the following steps:

[0020] Obtain the operating parameters of the compressor, and calculate the mass flow rate of the refrigerant at the liquid inlet of the flash evaporator based on the operating parameters; wherein, the operating parameters include the gas delivery coefficient, actual operating frequency, exhaust volume, and suction specific volume;

[0021] Obtain the refrigerant temperature, and calculate the first enthalpy value of the refrigerant at the liquid inlet of the flash evaporator based on the refrigerant temperature;

[0022] Based on the first enthalpy value, determine the second enthalpy value of the corresponding saturated liquid refrigerant and the third enthalpy value of the saturated dry vapor refrigerant;

[0023] The dryness of the refrigerant at the liquid inlet of the flash evaporator is calculated based on the first enthalpy value, the second enthalpy value, and the third enthalpy value.

[0024] Calculate the mass of saturated liquid refrigerant at the inlet of the flash evaporator based on the dryness and the mass flow rate.

[0025] Obtain the intermediate temperature and the critical temperature of the refrigerant, and calculate the density of the saturated liquid refrigerant at the inlet of the flash evaporator based on the intermediate temperature and the critical temperature.

[0026] Calculate the reciprocal of the density to obtain the specific volume of the saturated liquid refrigerant at the inlet of the flash evaporator;

[0027] The flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator is obtained by calculating the ratio of the product of the mass of the saturated liquid refrigerant at the inlet of the flash evaporator and the specific volume to the cross-sectional area of ​​the pipe at the inlet of the flash evaporator.

[0028] In the fourth embodiment of the present invention, the air conditioner wherein the calculation of the refrigerant mass flow rate at the liquid inlet of the flash evaporator based on the operating parameters specifically includes:

[0029] The mass flow rate of the refrigerant at the inlet of the flash evaporator is calculated using the following formula:

[0030] ;

[0031] in, The mass flow rate of the refrigerant at the inlet of the flash evaporator. The gas delivery coefficient of the compressor is given. This refers to the actual operating frequency of the compressor. The discharge capacity of the compressor. The specific volume of the compressor is its suction gas volume.

[0032] The air conditioner provided in the fifth embodiment of the present invention obtains the gas delivery coefficient of the compressor through the following steps:

[0033] Obtain the absolute discharge pressure, absolute suction pressure, and rated operating frequency of the compressor, and calculate the compressor's gas delivery coefficient using the following formula:

[0034] ;

[0035] in, The gas delivery coefficient of the compressor is given. The absolute discharge pressure of the compressor, The absolute suction pressure of the compressor, The rated operating frequency of the compressor. This refers to the actual operating frequency of the compressor. These are the first to sixth fitting coefficients.

[0036] The air conditioner provided in the sixth embodiment of the present invention further includes an indoor coil temperature detection device and a compressor suction temperature detection device; wherein,

[0037] The indoor coil temperature detection device is installed on the coil of the indoor heat exchanger and is used to detect the second saturation temperature corresponding to the evaporation pressure of the indoor heat exchanger.

[0038] The compressor suction temperature detection device is located at the suction port of the compressor and is used to detect the suction temperature of the compressor.

[0039] Then, the controller obtains the suction specific volume of the compressor through the following steps:

[0040] The second saturation temperature and the suction temperature are obtained, and the temperature difference between the suction temperature and the second saturation temperature is calculated to obtain the suction superheat of the compressor.

[0041] Obtain the saturated dry steam specific volume corresponding to the second saturation temperature, and calculate the compressor's suction specific volume according to the following formula:

[0042] ;

[0043] ;

[0044] in, The specific volume of the compressor is its suction gas volume. The specific volume of the saturated dry steam. The second saturation temperature, The intake superheat, These are the seventh to eighteenth fitting coefficients.

[0045] In the seventh embodiment of the present invention, the air conditioner wherein the calculation of the first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator based on the refrigerant temperature specifically involves:

[0046] The first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator is calculated according to the following formula:

[0047] ;

[0048] in, The first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator. The temperature of the refrigerant. These are the nineteenth to twenty-second fitting coefficients.

[0049] In the eighth embodiment of the present invention, the air conditioner wherein the calculation of the refrigerant dryness at the liquid inlet of the flash evaporator based on the first enthalpy value, the second enthalpy value, and the third enthalpy value specifically comprises:

[0050] The dryness of the refrigerant at the inlet of the flash evaporator is calculated using the following formula:

[0051] ;

[0052] in, The dryness of the refrigerant at the liquid inlet of the flash evaporator. This is the first enthalpy value. This is the second enthalpy value. This is the third enthalpy value.

[0053] In the ninth embodiment of the present invention, the air conditioner wherein the calculation of the mass of saturated liquid refrigerant at the inlet of the flash evaporator based on the dryness fraction and the mass flow rate specifically comprises:

[0054] The mass of the saturated liquid refrigerant at the inlet of the flash evaporator is calculated using the following formula:

[0055] ;

[0056] in, The mass of the saturated liquid refrigerant at the inlet of the flash evaporator. The dryness, The mass flow rate is denoted as .

[0057] The defrosting control method for an air conditioner provided in the tenth embodiment of the present invention includes a refrigerant circulation loop, a gas replenishment pressure detection device, and a gas replenishment temperature detection device. The refrigerant circulation loop includes a main circulation loop and a gas replenishment branch. The main circulation loop is composed of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling device, a flash evaporator, a second throttling device, and an indoor heat exchanger connected in sequence. The gas replenishment branch is located between the flash evaporator and the gas replenishment port of the compressor, and a gas replenishment valve is provided on the gas replenishment branch. The gas replenishment pressure detection device is located at the liquid inlet of the flash evaporator and is used to detect intermediate pressure. The gas replenishment temperature detection device is located at the liquid inlet of the flash evaporator and is used to detect intermediate temperature. The method includes:

[0058] When the air conditioner is in defrost mode, the intermediate pressure and intermediate temperature are obtained, the first saturation temperature corresponding to the intermediate pressure is queried, and the temperature difference between the first saturation temperature and the intermediate temperature is calculated.

[0059] When the temperature difference is detected to be zero, the gas supply valve is opened, and the charging time for liquid refrigerant to fill the flash evaporator is calculated.

[0060] When the cumulative time the air conditioner has been running in the defrost mode reaches the liquid filling time, the gas replenishment valve is controlled to close.

[0061] When the air conditioner is detected to meet the defrosting end conditions, the gas supply valve is closed and the defrosting mode is exited.

[0062] Compared to existing technologies, the air conditioner and its defrosting control method provided in this embodiment of the invention, when the temperature difference between the first saturation temperature corresponding to the intermediate pressure at the liquid inlet of the flash evaporator and the intermediate temperature at the liquid inlet of the flash evaporator is detected to be zero, controls the gas replenishment valve to open, thereby increasing the compressor's discharge volume during defrosting and shortening the defrosting time, thus achieving rapid defrosting to ensure stable indoor temperature and user comfort. Simultaneously, when the cumulative time of the air conditioner operating in the defrosting mode reaches the liquid refrigerant filling time of the flash evaporator, the gas replenishment valve is closed to avoid liquid return during gas replenishment and intake, ensuring stable compressor operation. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the structure of the first refrigerant circulation loop provided in an embodiment of the present invention.

[0064] Figure 2 This is a schematic diagram of the structure of a second refrigerant circulation loop provided in an embodiment of the present invention.

[0065] Figure 3 This is a schematic diagram of the structure of an air conditioner provided in an embodiment of the present invention.

[0066] Figure 4 This is a schematic diagram of the structure of an air conditioner control system provided in an embodiment of the present invention.

[0067] Figure 5 This is a pressure-enthalpy diagram of a refrigerant circulation loop in an air conditioner provided in an embodiment of the present invention.

[0068] Figure 6 This is a flowchart illustrating the process of a controller performing defrosting control according to an embodiment of the present invention.

[0069] Figure 7 This is a schematic diagram of another air conditioner control system provided in an embodiment of the present invention.

[0070] Figure 8 This is a schematic diagram of the third refrigerant circulation loop provided in an embodiment of the present invention.

[0071] Figure 9 This is a schematic diagram of the fourth refrigerant circulation loop provided in an embodiment of the present invention.

[0072] Figure 10 This is a schematic flowchart of a defrosting control method for an air conditioner provided in an embodiment of the present invention. Detailed Implementation

[0073] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0074] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0075] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0076] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0077] See Figure 1 This is a schematic diagram of the structure of the first refrigerant circulation loop provided in an embodiment of the present invention.

[0078] The air conditioner 100 of the present invention includes a refrigerant circulation loop; wherein, the refrigerant circulation loop includes a main circulation loop and a make-up gas branch, the main circulation loop is composed of a compressor 101, a four-way valve 102, an outdoor heat exchanger 103, a first throttling device 104, a flash evaporator 105, a second throttling device 106 and an indoor heat exchanger 107 connected in sequence; the make-up gas branch is located between the flash evaporator 105 and the make-up gas port of the compressor 101, and a make-up gas valve 108 is provided on the make-up gas branch. Specifically, in the refrigerant circulation loop, the discharge port of compressor 101 is connected to the first end d of four-way valve 102 via a connecting pipe; the second end c of four-way valve 102 is connected to the coarse pipe of outdoor heat exchanger 103 via a connecting pipe; the thin pipe of outdoor heat exchanger 103 is connected to the first end of first throttling device 104 via a connecting pipe; the second end of first throttling device 104 is connected to the liquid inlet of flash evaporator 105 via a connecting pipe; the gas supply port of flash evaporator 105 is connected to compressor 101 via gas supply valve 108; the liquid outlet of flash evaporator 105 is connected to the first end of second throttling device 106 via a connecting pipe; the second end of second throttling device 106 is connected to the thin pipe of indoor heat exchanger 107 via a connecting pipe; the coarse pipe of indoor heat exchanger 107 is connected to the third end e of four-way valve 102 via a connecting pipe; and the fourth end s of four-way valve 102 is connected to the suction port of compressor 101. Specifically, the first throttling device 104 and the second throttling device 106 are electronic expansion valves. See also... Figure 2 The air conditioner 100 also includes an outdoor fan 111 and an indoor fan 112; wherein the outdoor fan 111 is disposed relative to the outdoor heat exchanger 103, and the indoor fan 112 is disposed relative to the indoor heat exchanger 107.

[0079] See Figure 3 The air conditioner 100 of the present invention also includes an indoor unit 30, which is used to regulate the temperature and humidity of indoor air. Taking a wall-mounted unit (shown in the figure) as an example, the indoor unit is usually installed on an indoor wall such as a wall panel (WL). Another example is a floor-standing unit (not shown in the figure), which is also a form of indoor unit 30. The aforementioned indoor heat exchanger 107 and indoor fan 112 are located in the indoor unit 30. The air conditioner 100 also includes an outdoor unit 20, which is usually installed outdoors and connected to the indoor unit 30 via a connecting pipe 40 for heat exchange with the indoor environment. Furthermore, in Figure 3 In the diagram, outdoor unit 20 is represented by a dashed line because it is located outdoors on the opposite side of the wall WL, opposite to indoor unit 30. Furthermore, as... Figure 3 As shown, the air conditioner 100 also includes a remote control 50, which has the following functions: Figure 3The liquid crystal display device 5a and button 5b shown are included. The remote control 50 has the function of communicating with the controller 60, for example, using infrared or other communication methods. The remote control is used by the user to perform various controls on the air conditioner 100, enabling interaction between the user and the air conditioner 100.

[0080] See Figure 1 The air conditioner 100 provided in this embodiment of the invention further includes a gas supply pressure detection device 109 and a gas supply temperature detection device 110; wherein, the gas supply pressure detection device 109 is located at the liquid inlet of the flash evaporator 105 and is used to detect the intermediate pressure; the gas supply temperature detection device 110 is located at the liquid inlet of the flash evaporator 105 and is used to detect the intermediate temperature; see also Figure 3 The air conditioner 100 also includes a controller 60, which is connected to a gas supply pressure detection device 109 to receive the intermediate pressure detected by the gas supply pressure detection device 109; the controller 60 is also connected to a gas supply temperature detection device 110 to receive the intermediate temperature detected by the gas supply temperature detection device 110; and the controller 60 is also connected to a gas supply valve 108 to control the gas supply valve 108. Specifically, the controller 60 is used for:

[0081] When the air conditioner 100 is in defrost mode, the intermediate pressure and intermediate temperature are obtained, the first saturation temperature corresponding to the intermediate pressure is queried, and the temperature difference between the first saturation temperature and the intermediate temperature is calculated.

[0082] When the temperature difference is detected to be zero, the gas supply valve 108 is opened, and the filling time for liquid refrigerant to fill the flash evaporator 105 is calculated.

[0083] When the cumulative time that the air conditioner 100 has been running the defrost mode reaches the liquid filling time, the air supply valve 108 is controlled to close.

[0084] When the air conditioner 100 is detected to meet the defrosting end conditions, the air supply valve 108 is closed and the defrosting mode is exited.

[0085] In this embodiment, when the air conditioner 100 detects that the temperature difference between the first saturation temperature corresponding to the intermediate pressure at the liquid inlet of the flash evaporator 105 and the intermediate temperature at the liquid inlet of the flash evaporator 105 is equal to zero, it controls the gas replenishment valve 108 to open. This replenishment increases the discharge volume of the compressor 101 during defrosting, shortening the defrosting time and achieving rapid defrosting to ensure stable indoor temperature and user comfort. Simultaneously, when the cumulative time of the air conditioner 100 operating the defrosting mode reaches the liquid refrigerant filling time of the flash evaporator 105, it controls the gas replenishment valve 108 to close. This prevents liquid return during gas replenishment and intake, ensuring stable operation of the compressor 101.

[0086] It is worth noting that when the air conditioner 100 is detected to meet the defrosting conditions, it enters defrosting mode. The air conditioner 100 uses reverse defrosting as its basic defrosting method, meaning that the main circulation loop is controlled to deliver refrigerant according to the defrosting refrigerant flow direction, while the gas supply valve 108 remains closed. Specifically, the defrosting refrigerant flow of the air conditioner 100 is as follows: refrigerant gas is discharged from the compressor 101, reversed through the four-way valve 102, and enters the outdoor heat exchanger 103. The refrigerant condenses and releases heat to defrost. After defrosting, the refrigerant then enters the flash evaporator 105 through the first throttling device 104 and flows to the indoor heat exchanger 107. After absorbing heat in the indoor heat exchanger 107, it flows back to the compressor 101 for intake through the four-way valve 102, completing the entire defrosting cycle. However, this defrosting method has a longer defrosting time, which can easily lead to a decrease in indoor temperature and affect user comfort. In existing gas-fueled enthalpy-increasing refrigeration systems, using a flash evaporator 105 as an intermediate gas-fueled gas-liquid separation device is one of the main system forms. The working principle of the gas-fueled enthalpy-increasing refrigeration system with flash evaporator 105 is as follows: the high-temperature and high-pressure refrigerant gas from the compressor 101 enters the condenser and releases heat. After a first-stage throttling, it enters the flash evaporator 105. Based on the physical principle that the gas density is less than the liquid density, the flash evaporator 105 separates the flashed gaseous refrigerant gas after throttling. This gas is then drawn into the gas-fueled port of the refrigeration compressor 101. The flashed liquid refrigerant, after a second-stage throttling, becomes a low-temperature and low-pressure state and enters the evaporator. After absorbing heat from the environment, it becomes a low-temperature and low-pressure gas and enters the suction port of the compressor 101. The compressor 101 compresses this portion of refrigerant to an intermediate pressure and mixes it with the refrigerant gas at the intermediate pressure of the gas-fueled port. The mixture is then further compressed until it becomes a high-temperature and high-pressure refrigerant gas. This cycle is the working principle of the gas-fueled enthalpy-increasing refrigeration system. During the system's cyclic operation, the refrigeration compressor 101 increases its discharge volume due to the increased intermediate gas supply, thereby improving the heating capacity of the air conditioner 100. Therefore, in this embodiment, in addition to the original defrosting mode, it further determines whether the gas supply valve 108 can be opened based on the first saturation temperature and the intermediate temperature corresponding to the intermediate pressure at the liquid inlet of the flash evaporator 105. When the temperature difference between the first saturation temperature and the intermediate temperature is zero, the gas supply valve 108 is opened, and the discharge volume of the refrigeration compressor 101 is increased by gas supply through the flash evaporator 105 to achieve the purpose of rapid defrosting. At the same time, when the liquid refrigerant fills the flash evaporator 105, the gas supply valve 108 is closed to avoid the phenomenon of liquid return during gas supply and suction.

[0087] Specifically, the opening degree of the first throttling device 104 and the second throttling device 106 is a preset value.

[0088] It is worth noting that, during the defrosting process, in order to further avoid the liquid return phenomenon during air replenishment and air intake, both the first throttling device 104 and the second throttling device 106 adopt fixed opening control.

[0089] See Figure 5 When the air conditioner 100 is in defrost mode, according to the pressure-enthalpy diagram of the refrigerant circulation loop, the refrigerant flow direction during defrost is 4, 5, 6, 7, 9, 1, 2, 3, 4. The condition for whether the gas replenishment valve 108 is open is based on the refrigerant state at point 6, that is, the refrigerant state at the liquid inlet of the flash evaporator 105 after the first throttling device 104 has performed a first-stage throttling. When the temperature difference between the first saturation temperature corresponding to the intermediate pressure at the liquid inlet of the flash evaporator 105 and the intermediate temperature at the liquid inlet of the flash evaporator 105 is greater than zero, the gas replenishment valve 108 is not opened. When the temperature difference is equal to zero, the gas replenishment valve 108 is opened, using gas replenishment to increase the displacement of the compressor 101 to achieve rapid defrosting. At the same time, after the gas replenishment valve 108 is opened, if the liquid refrigerant fills the flash evaporator 105, the gas replenishment valve 108 needs to be closed to avoid liquid return.

[0090] Specifically, controller 60 is also used for:

[0091] When the air conditioner 100 is detected to meet the defrost start conditions, the air conditioner 100 is controlled to enter the defrost mode, the gas supply valve 108 is kept closed, and the main circulation circuit is controlled to deliver refrigerant according to the defrost refrigerant flow direction.

[0092] It should be noted that the defrosting start and defrosting end conditions can be found in other relevant literature, and will not be elaborated on further here.

[0093] For example, combined Figure 6The diagram shows a flowchart of a controller performing defrosting control according to an embodiment of the present invention. The specific process of the controller 60 performing defrosting control is as follows: When the air conditioner 100 is in defrosting mode, the intermediate pressure and intermediate temperature at the liquid inlet of the flash evaporator 105 are obtained (step S11), and then step S12 is executed; the first saturation temperature corresponding to the intermediate pressure is queried (step S12), and then step S13 is executed; the temperature difference between the first saturation temperature and the intermediate temperature is calculated (step S13), and then step S14 is executed; it is determined whether the temperature difference is equal to zero (step S14). If it is, step S15 is executed; otherwise, step S16 is executed; the gas supply valve 108 is opened (step S15), and then step S17 is executed. 17; Keep the gas supply valve 108 closed, continue to control the main circulation loop to deliver refrigerant according to the defrosting refrigerant flow direction (step S16), and then execute step S20; calculate the liquid charging time for the liquid refrigerant to fill the flash evaporator 105 (step S17), and then execute step S18; determine whether the cumulative time of the air conditioner 100 running the defrosting mode has reached the liquid charging time (step S18). If yes, execute step S19; otherwise, execute step S20; control the gas supply valve 108 to close, continue to control the main circulation loop to deliver refrigerant according to the defrosting refrigerant flow direction (step S19), and then execute step S20; when the air conditioner 100 meets the defrosting end condition, exit the defrosting mode (step S20), and this defrosting ends.

[0094] As one specific embodiment, the calculation of the liquid refrigerant filling time of the flash evaporator 105 includes:

[0095] Obtain the flow rate of saturated liquid refrigerant at the inlet of flash evaporator 105 and the internal volume of flash evaporator 105;

[0096] The ratio of the internal volume to the flow rate is calculated to obtain the filling time for the liquid refrigerant to fill the flash evaporator 105.

[0097] It should be noted that the refrigerant at the inlet of the flash evaporator 105 is a two-phase refrigerant, comprising both gaseous and liquid refrigerant. Therefore, when calculating the filling time for the liquid refrigerant to fill the flash evaporator 105, it is necessary to obtain the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator 105. This flow rate, combined with the pre-obtained internal volume of the flash evaporator 105, determines the filling time for the liquid refrigerant to fill the flash evaporator 105. This ensures that the gas supply valve 108 is closed when the flash evaporator 105 is full, preventing liquid backflow.

[0098] See Figure 7 and Figure 8 Furthermore, the air conditioner 100 also includes: a refrigerant temperature detection device 113; wherein,

[0099] A refrigerant temperature detection device 113 is installed on the pipeline between the outdoor heat exchanger 103 and the first throttling device 104, and is used to detect the refrigerant temperature between the outdoor heat exchanger 103 and the first throttling device 104.

[0100] Then, the controller 60 obtains the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator 105 through the following steps:

[0101] Obtain the operating parameters of compressor 101, and calculate the mass flow rate of refrigerant at the liquid inlet of flash evaporator 105 based on the operating parameters; wherein, the operating parameters include gas delivery coefficient, actual operating frequency, discharge volume, and suction specific volume;

[0102] Obtain the refrigerant temperature, and calculate the first enthalpy value of the refrigerant at the liquid inlet of the flash evaporator 105 based on the refrigerant temperature;

[0103] Based on the first enthalpy value, determine the second enthalpy value of the corresponding saturated liquid refrigerant and the third enthalpy value of the saturated dry vapor refrigerant;

[0104] The dryness of the refrigerant at the liquid inlet of the flash evaporator 105 is calculated based on the first enthalpy value, the second enthalpy value, and the third enthalpy value.

[0105] Calculate the mass of saturated liquid refrigerant at the inlet of flash evaporator 105 based on the dryness and the mass flow rate.

[0106] Obtain the intermediate temperature and the critical temperature of the refrigerant, and calculate the density of the saturated liquid refrigerant at the liquid inlet of the flash evaporator 105 based on the intermediate temperature and the critical temperature.

[0107] Calculate the reciprocal of the density to obtain the specific volume of the saturated liquid refrigerant at the inlet of the flash evaporator 105;

[0108] The flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator 105 is obtained by calculating the ratio of the product of the mass of the saturated liquid refrigerant at the inlet of the flash evaporator 105 and the specific volume to the cross-sectional area of ​​the pipe at the inlet of the flash evaporator 105.

[0109] It is worth noting that in actual operation, the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator 105 can be measured using other flow rate measuring devices. However, considering that installing such flow rate measuring devices would disrupt the refrigeration system of the air conditioner 100 to some extent, in this embodiment, the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator 105 is obtained using the aforementioned series of calculations. Furthermore, it should be noted that after the refrigerant undergoes primary throttling by the first throttling device 104, the refrigerant at the liquid inlet of the flash evaporator 105 is a two-phase refrigerant. Since the two-phase refrigerant contains both gaseous and liquid refrigerant, calculating the enthalpy of the two-phase refrigerant at the liquid inlet of the flash evaporator 105 requires calculating the proportions of gaseous and liquid refrigerant separately, measuring the temperatures of the gaseous and liquid refrigerants, calculating the corresponding enthalpy based on the temperatures of the gaseous and liquid refrigerants, and then calculating a weighted average based on the proportions of gaseous and liquid refrigerants to weight the enthalpy value. Only then can the first enthalpy value of the refrigerant at the liquid inlet of the flash evaporator 105 be obtained, making the calculation relatively complex. Based on this, considering that the enthalpy of the refrigerant at both ends of the first throttling device 104 is equal before and after the first throttling of the refrigerant by the first throttling device 104, and that the refrigerant is in a pure liquid state before the first throttling by the first throttling device 104, the enthalpy of the refrigerant at this time corresponds one-to-one with the refrigerant temperature. Therefore, the enthalpy of the refrigerant between the outdoor heat exchanger 103 and the first throttling device 104 can be calculated by measuring the refrigerant temperature between the outdoor heat exchanger 103 and the first throttling device 104. Figure 5 The enthalpy value at point 5 is used to obtain the enthalpy value of the refrigerant between the outdoor heat exchanger 103 and the first throttling device 104, and then the enthalpy value at the liquid inlet of the flash evaporator 105 is obtained, which is the first enthalpy value. This greatly simplifies the calculation process of the first enthalpy value at the liquid inlet of the flash evaporator 105.

[0110] As one specific embodiment, the calculation of the refrigerant mass flow rate at the liquid inlet of the flash evaporator 105 based on the operating parameters is specifically as follows:

[0111] Calculate the mass flow rate of the refrigerant at the liquid inlet of flash evaporator 105 using the following formula:

[0112] ;

[0113] in, This refers to the mass flow rate of the refrigerant at the liquid inlet of the flash evaporator 105. The gas delivery coefficient of compressor 101 This refers to the actual operating frequency of compressor 101. This refers to the discharge capacity of compressor 101. This refers to the suction specific volume of compressor 101.

[0114] Furthermore, the controller 60 obtains the gas delivery coefficient of the compressor 101 through the following steps:

[0115] Obtain the absolute discharge pressure, absolute suction pressure, and rated operating frequency of compressor 101, and calculate the gas delivery coefficient of compressor 101 according to the following formula:

[0116] ;

[0117] in, The gas delivery coefficient of compressor 101 The absolute pressure of the compressor 101's discharge. The absolute suction pressure of compressor 101, The rated operating frequency of compressor 101, This refers to the actual operating frequency of compressor 101. These are the first to sixth fitting coefficients.

[0118] It should be noted that the first fitting coefficient Second fitting coefficient Third fitting coefficient Fourth fitting coefficient Fifth fitting coefficient The sixth fitting coefficient This can be obtained through experiments or by fitting partial load data provided by the compressor 101 manufacturer. Understandably, the experimental data or the load data should include several corresponding absolute discharge pressures of the compressor 101, absolute suction pressures of the compressor 101, rated operating frequencies of the compressor 101, and historical operating frequencies.

[0119] See Figure 9 As one specific implementation, the air conditioner 100 further includes an indoor coil temperature detection device 114 and a compressor suction temperature detection device 115; wherein,

[0120] The indoor coil temperature detection device 114 is installed on the coil of the indoor heat exchanger 107 and is used to detect the second saturation temperature corresponding to the evaporation pressure of the indoor heat exchanger 107.

[0121] The compressor suction temperature detection device 115 is located at the suction port of the compressor 101 and is used to detect the suction temperature of the compressor 101.

[0122] Then, the controller 60 obtains the suction specific volume of the compressor 101 through the following steps:

[0123] The second saturation temperature and the suction temperature are obtained, and the temperature difference between the suction temperature and the second saturation temperature is calculated to obtain the suction superheat of the compressor 101.

[0124] Obtain the saturated dry steam specific volume corresponding to the second saturation temperature, and calculate the suction specific volume of compressor 101 according to the following formula:

[0125] ;

[0126] ;

[0127] in, The suction specific volume of compressor 101, The specific volume of the saturated dry steam. The second saturation temperature, The intake superheat, These are the seventh to eighteenth fitting coefficients.

[0128] It should be noted that the seventh fitting coefficient up to the eighteenth fitting coefficient This information can be obtained from literature or relevant refrigerant parameter calculation manuals.

[0129] As one specific implementation, the calculation of the refrigerant dryness at the liquid inlet of the flash evaporator 105 based on the first enthalpy value, the second enthalpy value, and the third enthalpy value specifically involves:

[0130] Calculate the dryness of the refrigerant at the inlet of flash evaporator 105 using the following formula:

[0131] ;

[0132] in, The dryness of the refrigerant at the liquid inlet of flash evaporator 105. This is the first enthalpy value. This is the second enthalpy value. This is the third enthalpy value.

[0133] Further, the calculation of the first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator 105 based on the refrigerant temperature specifically involves:

[0134] Calculate the first enthalpy of the liquid refrigerant at the inlet of flash evaporator 105 using the following formula:

[0135] ;

[0136] in, The first enthalpy value of the liquid refrigerant at the inlet of flash evaporator 105. The temperature of the refrigerant. These are the nineteenth to twenty-second fitting coefficients.

[0137] It should be noted that the nineteenth to twenty-second fitting coefficients can be obtained from literature or relevant refrigerant parameter calculation manuals.

[0138] Specifically, the calculation of the density of the saturated liquid refrigerant at the inlet of the flash evaporator 105 based on the intermediate temperature and the critical temperature is as follows:

[0139] Calculate the density of the saturated liquid refrigerant at the inlet of flash evaporator 105 using the following formula:

[0140] ;

[0141] in, The density of the saturated liquid refrigerant at the inlet of flash evaporator 105. The intermediate temperature, The critical temperature is... These are the twenty-third to twenty-seventh fitting coefficients.

[0142] It should be noted that the fitting coefficients from the 23rd to the 27th can be obtained from literature or relevant refrigerant parameter calculation manuals. Furthermore, different refrigerants have different critical temperatures, which can be found in refrigerant physical property tables.

[0143] Further, the calculation of the mass of saturated liquid refrigerant at the inlet of flash evaporator 105 based on the dryness fraction and the mass flow rate specifically involves:

[0144] Calculate the mass of the saturated liquid refrigerant at the inlet of flash evaporator 105 using the following formula:

[0145] ;

[0146] in, The mass of the saturated liquid refrigerant at the inlet of flash evaporator 105. The dryness, The mass flow rate is denoted as .

[0147] See Figure 10 This is a flowchart illustrating a defrosting control method for an air conditioner provided in an embodiment of the present invention.

[0148] The defrosting control method for an air conditioner provided in this embodiment includes a refrigerant circulation loop, a gas replenishment pressure detection device, and a gas replenishment temperature detection device. The refrigerant circulation loop includes a main circulation loop and a gas replenishment branch. The main circulation loop is composed of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling device, a flash evaporator, a second throttling device, and an indoor heat exchanger connected in sequence. The gas replenishment branch is located between the flash evaporator and the gas replenishment port of the compressor, and a gas replenishment valve is provided on the gas replenishment branch. The gas replenishment pressure detection device is located at the liquid inlet of the flash evaporator and is used to detect intermediate pressure. The gas replenishment temperature detection device is located at the liquid inlet of the flash evaporator and is used to detect intermediate temperature. The method includes:

[0149] Step S1: When the air conditioner is in defrost mode, obtain the intermediate pressure and intermediate temperature, query the first saturation temperature corresponding to the intermediate pressure, and calculate the temperature difference between the first saturation temperature and the intermediate temperature.

[0150] Step S2: When the temperature difference is detected to be zero, control the gas supply valve to open and calculate the liquid refrigerant filling time of the flash evaporator.

[0151] Step S3: When the cumulative time of the air conditioner running the defrost mode reaches the liquid filling time, control the gas replenishment valve to close;

[0152] Step S4: When the air conditioner is detected to meet the defrosting end conditions, control the gas supply valve to close and exit the defrosting mode.

[0153] In the defrosting control method for an air conditioner provided in this embodiment, when the temperature difference between the first saturation temperature corresponding to the intermediate pressure at the liquid inlet of the flash evaporator and the intermediate temperature at the liquid inlet of the flash evaporator is detected to be zero, the gas replenishment valve is opened. Gas replenishment increases the compressor's discharge volume during defrosting, thereby shortening the defrosting time and achieving rapid defrosting to ensure stable indoor temperature and user comfort. Simultaneously, when the cumulative time the air conditioner has run in the defrosting mode reaches the liquid refrigerant filling time of the flash evaporator, the gas replenishment valve is closed to prevent liquid return during gas replenishment and intake, ensuring stable compressor operation.

[0154] As one specific embodiment, the calculation of the liquid refrigerant filling time of the flash evaporator includes:

[0155] Obtain the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator and the internal volume of the flash evaporator;

[0156] The ratio of the internal volume to the flow rate is calculated to obtain the filling time for the liquid refrigerant to fill the flash evaporator.

[0157] Furthermore, the air conditioner also includes: a refrigerant temperature detection device; wherein, the refrigerant temperature detection device is located on the pipeline between the outdoor heat exchanger and the first throttling device, and is used to detect the refrigerant temperature between the outdoor heat exchanger and the first throttling device; then, the flow rate of saturated liquid refrigerant at the inlet of the flash evaporator is obtained through the following steps:

[0158] Obtain the operating parameters of the compressor, and calculate the mass flow rate of the refrigerant at the liquid inlet of the flash evaporator based on the operating parameters; wherein, the operating parameters include the gas delivery coefficient, actual operating frequency, exhaust volume, and suction specific volume;

[0159] Obtain the refrigerant temperature, and calculate the first enthalpy value of the refrigerant at the liquid inlet of the flash evaporator based on the refrigerant temperature;

[0160] Based on the first enthalpy value, determine the second enthalpy value of the corresponding saturated liquid refrigerant and the third enthalpy value of the saturated dry vapor refrigerant;

[0161] The dryness of the refrigerant at the liquid inlet of the flash evaporator is calculated based on the first enthalpy value, the second enthalpy value, and the third enthalpy value.

[0162] Calculate the mass of saturated liquid refrigerant at the inlet of the flash evaporator based on the dryness and the mass flow rate.

[0163] Obtain the intermediate temperature and the critical temperature of the refrigerant, and calculate the density of the saturated liquid refrigerant at the inlet of the flash evaporator based on the intermediate temperature and the critical temperature.

[0164] Calculate the reciprocal of the density to obtain the specific volume of the saturated liquid refrigerant at the inlet of the flash evaporator;

[0165] The flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator is obtained by calculating the ratio of the product of the mass of the saturated liquid refrigerant at the inlet of the flash evaporator and the specific volume to the cross-sectional area of ​​the pipe at the inlet of the flash evaporator.

[0166] As one specific embodiment, the gas delivery coefficient of the compressor is obtained through the following steps:

[0167] Obtain the absolute discharge pressure, absolute suction pressure, and rated operating frequency of the compressor, and calculate the compressor's gas delivery coefficient using the following formula:

[0168] ;

[0169] in, The gas delivery coefficient of the compressor is given. The absolute discharge pressure of the compressor, The absolute suction pressure of the compressor, The rated operating frequency of the compressor. This refers to the actual operating frequency of the compressor. These are the first to sixth fitting coefficients.

[0170] Furthermore, the air conditioner also includes an indoor coil temperature detection device and a compressor suction temperature detection device; wherein, the indoor coil temperature detection device is located on the coil of the indoor heat exchanger and is used to detect the second saturation temperature corresponding to the evaporation pressure of the indoor heat exchanger; the compressor suction temperature detection device is located at the suction port of the compressor and is used to detect the suction temperature of the compressor; then, the suction specific volume of the compressor is obtained through the following steps:

[0171] The second saturation temperature and the suction temperature are obtained, and the temperature difference between the suction temperature and the second saturation temperature is calculated to obtain the suction superheat of the compressor.

[0172] Obtain the saturated dry steam specific volume corresponding to the second saturation temperature, and calculate the compressor's suction specific volume according to the following formula:

[0173] ;

[0174] ;

[0175] in, The specific volume of the compressor is its suction gas volume. The specific volume of the saturated dry steam. The second saturation temperature, The intake superheat, These are the seventh to eighteenth fitting coefficients.

[0176] As one specific implementation, the calculation of the first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator based on the refrigerant temperature specifically involves:

[0177] The first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator is calculated according to the following formula:

[0178] ;

[0179] in, The first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator. The temperature of the refrigerant. These are the nineteenth to twenty-second fitting coefficients.

[0180] As one specific implementation, the step of calculating the dryness of the refrigerant at the liquid inlet of the flash evaporator based on the first enthalpy value, the second enthalpy value, and the third enthalpy value specifically involves:

[0181] The dryness of the refrigerant at the inlet of the flash evaporator is calculated using the following formula:

[0182] ;

[0183] in, The dryness of the refrigerant at the liquid inlet of the flash evaporator. This is the first enthalpy value. This is the second enthalpy value. This is the third enthalpy value.

[0184] Further, the calculation of the mass of saturated liquid refrigerant at the inlet of the flash evaporator based on the dryness fraction and the mass flow rate specifically involves:

[0185] The mass of the saturated liquid refrigerant at the inlet of the flash evaporator is calculated using the following formula:

[0186] ;

[0187] in, The mass of the saturated liquid refrigerant at the inlet of the flash evaporator. The dryness, The mass flow rate is denoted as .

[0188] The specific description of the defrosting control method for the air conditioner provided in this embodiment can be found in the specific descriptions of the various embodiments of the air conditioner described above, and will not be repeated here.

[0189] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0190] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An air conditioner characterized by comprising: include: The refrigerant circulation loop includes a main circulation loop and a make-up gas branch; wherein, the main circulation loop is composed of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling device, a flash evaporator, a second throttling device, and an indoor heat exchanger connected in sequence; the make-up gas branch is located between the flash evaporator and the make-up gas port of the compressor, and the make-up gas branch is equipped with a make-up gas valve; A gas replenishment pressure detection device is installed at the liquid inlet of the flash evaporator to detect the intermediate pressure; A gas replenishment temperature detection device is installed at the liquid inlet of the flash evaporator to detect the intermediate temperature; Controller, used for: When the air conditioner is detected to meet the defrosting conditions, the air conditioner enters the defrosting mode and uses reverse defrosting as the basic defrosting method. The intermediate pressure and intermediate temperature are obtained, the first saturation temperature corresponding to the intermediate pressure is queried, and the temperature difference between the first saturation temperature and the intermediate temperature is calculated. When the temperature difference is detected to be zero, the gas supply valve is opened, and the charging time for liquid refrigerant to fill the flash evaporator is calculated. When the cumulative time the air conditioner has been running in the defrost mode reaches the liquid filling time, the gas replenishment valve is controlled to close. When the air conditioner is detected to meet the defrosting end conditions, the gas supply valve is closed and the defrosting mode is exited.

2. The air conditioner of claim 1, wherein The calculation of the liquid refrigerant filling time of the flash evaporator includes: Obtain the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator and the internal volume of the flash evaporator; The ratio of the internal volume to the flow rate is calculated to obtain the filling time for the liquid refrigerant to fill the flash evaporator.

3. The air conditioner of claim 2, wherein The air conditioner also includes: a refrigerant temperature detection device; wherein... The refrigerant temperature detection device is installed on the pipeline between the outdoor heat exchanger and the first throttling device, and is used to detect the refrigerant temperature between the outdoor heat exchanger and the first throttling device. Then, the controller obtains the flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator through the following steps: Obtain the operating parameters of the compressor, and calculate the mass flow rate of the refrigerant at the liquid inlet of the flash evaporator based on the operating parameters; wherein, the operating parameters include the gas delivery coefficient, actual operating frequency, exhaust volume, and suction specific volume; Obtain the refrigerant temperature, and calculate the first enthalpy value of the refrigerant at the liquid inlet of the flash evaporator based on the refrigerant temperature; Based on the first enthalpy value, determine the second enthalpy value of the corresponding saturated liquid refrigerant and the third enthalpy value of the saturated dry vapor refrigerant; The dryness of the refrigerant at the liquid inlet of the flash evaporator is calculated based on the first enthalpy value, the second enthalpy value, and the third enthalpy value. Calculate the mass of saturated liquid refrigerant at the inlet of the flash evaporator based on the dryness and the mass flow rate. Obtain the intermediate temperature and the critical temperature of the refrigerant, and calculate the density of the saturated liquid refrigerant at the inlet of the flash evaporator based on the intermediate temperature and the critical temperature. Calculate the reciprocal of the density to obtain the specific volume of the saturated liquid refrigerant at the inlet of the flash evaporator; The flow rate of the saturated liquid refrigerant at the inlet of the flash evaporator is obtained by calculating the ratio of the product of the mass of the saturated liquid refrigerant at the inlet of the flash evaporator and the specific volume to the cross-sectional area of ​​the pipe at the inlet of the flash evaporator.

4. The air conditioner of claim 3, wherein The calculation of the refrigerant mass flow rate at the liquid inlet of the flash evaporator based on the operating parameters is specifically as follows: The mass flow rate of the refrigerant at the inlet of the flash evaporator is calculated using the following formula: ； in, The mass flow rate of the refrigerant at the inlet of the flash evaporator. The gas delivery coefficient of the compressor is given. This refers to the actual operating frequency of the compressor. The discharge capacity of the compressor. The specific volume of the compressor is its suction gas volume.

5. The air conditioner of claim 3, wherein The controller obtains the gas delivery coefficient of the compressor through the following steps: Obtain the absolute discharge pressure, absolute suction pressure, and rated operating frequency of the compressor, and calculate the compressor's gas delivery coefficient using the following formula: ； in, The gas delivery coefficient of the compressor is... The absolute discharge pressure of the compressor, The absolute suction pressure of the compressor, The rated operating frequency of the compressor. This refers to the actual operating frequency of the compressor. These are the first to sixth fitting coefficients.

6. The air conditioner of claim 3, wherein The air conditioner also includes an indoor coil temperature detection device and a compressor suction temperature detection device; wherein... The indoor coil temperature detection device is installed on the coil of the indoor heat exchanger and is used to detect the second saturation temperature corresponding to the evaporation pressure of the indoor heat exchanger. The compressor suction temperature detection device is located at the suction port of the compressor and is used to detect the suction temperature of the compressor. Then, the controller obtains the suction specific volume of the compressor through the following steps: The second saturation temperature and the suction temperature are obtained, and the temperature difference between the suction temperature and the second saturation temperature is calculated to obtain the suction superheat of the compressor. Obtain the saturated dry steam specific volume corresponding to the second saturation temperature, and calculate the compressor's suction specific volume according to the following formula: ； ； in, The specific volume of the compressor is its suction gas volume. The specific volume of the saturated dry steam. The second saturation temperature, The intake superheat, These are the seventh to eighteenth fitting coefficients.

7. The air conditioner of claim 3, wherein The calculation of the first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator based on the refrigerant temperature is specifically as follows: The first enthalpy value of the liquid refrigerant at the inlet of the flash evaporator is calculated according to the following formula: ； wherein, H1 is a first enthalpy value of the liquid refrigerant at the flash evaporator inlet, T1 is the refrigerant temperature, the nineteenth through twenty-second fitting coefficients.

8. The air conditioner of claim 3, wherein The step of calculating the dryness of the refrigerant at the liquid inlet of the flash evaporator based on the first enthalpy value, the second enthalpy value, and the third enthalpy value is specifically as follows: The dryness of the refrigerant at the inlet of the flash evaporator is calculated using the following formula: ； in, The dryness of the refrigerant at the liquid inlet of the flash evaporator. This is the first enthalpy value. This is the second enthalpy value. This is the third enthalpy value.

9. The air conditioner of claim 3, wherein The calculation of the mass of saturated liquid refrigerant at the inlet of the flash evaporator based on the dryness fraction and the mass flow rate is specifically as follows: The mass of the saturated liquid refrigerant at the inlet of the flash evaporator is calculated using the following formula: ； wherein, is the mass of saturated liquid refrigerant at the flash tank inlet, is the dryness, is the mass flow rate.

10. A defrosting control method of an air conditioner, characterized by, The air conditioner includes a refrigerant circulation loop, a refrigerant pressure detection device, and a refrigerant temperature detection device; wherein, the refrigerant circulation loop includes a main circulation loop and a refrigerant branch, the main circulation loop being composed of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling device, a flash evaporator, a second throttling device, and an indoor heat exchanger connected in sequence, the refrigerant branch being located between the flash evaporator and the refrigerant inlet of the compressor, and having a refrigerant valve on the refrigerant branch; the refrigerant pressure detection device is located at the liquid inlet of the flash evaporator and is used to detect intermediate pressure; the refrigerant temperature detection device is located at the liquid inlet of the flash evaporator and is used to detect intermediate temperature; therefore, the method includes: When the air conditioner is detected to meet the defrosting conditions, the air conditioner enters the defrosting mode and uses reverse defrosting as the basic defrosting method. The intermediate pressure and intermediate temperature are obtained, the first saturation temperature corresponding to the intermediate pressure is queried, and the temperature difference between the first saturation temperature and the intermediate temperature is calculated. When the temperature difference is detected to be zero, the gas supply valve is opened, and the charging time for liquid refrigerant to fill the flash evaporator is calculated. When the cumulative time the air conditioner has been running in the defrost mode reaches the liquid filling time, the gas replenishment valve is controlled to close. When the air conditioner is detected to meet the defrosting end conditions, the gas supply valve is closed and the defrosting mode is exited.

Images