JP2015230153A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of properly performing a defrosting operation.SOLUTION: An air conditioner includes: a refrigerant circuit in which a compressor 21, a flow passage switcher 22, an outdoor heat exchanger 23, a throttle device 24, and an indoor heat exchanger 25 are connected through refrigerant piping 51; a temperature sensor 61 which is provided on an entrance side of the outdoor heat exchanger 23, and detects an entrance temperature; and an outdoor controller 63 which performs a defrosting operation. The outdoor controller 63 has: correction value arithmetic means 73 of computing a correction value based upon a flow rate of a refrigerant circulating in the refrigerant circuit; intermediate temperature derivation means 75 of deriving an intermediate temperature of an intermediate part of the outdoor heat exchanger 23 based upon the entrance temperature detected by the temperature sensor 61 and the correction value computed by the correction value arithmetic means 73; and operation mode control means 71 of performing the defrosting operation based upon the intermediate temperature derived by the intermediate temperature derivation means 75.

Description

  The present invention relates to an air conditioner that performs defrosting control.

  Conventionally, when an air conditioner continues a heating operation, an outdoor heat exchanger serving as an evaporator forms frost, and therefore, a defrosting operation is performed (for example, see Patent Document 1). The technique described in Patent Literature 1 performs air conditioning control based on the average temperature of the evaporator obtained based on the heat load factor of the evaporator and the detection result of the temperature on the inlet side that is the lowest temperature of the evaporator. This prevents the evaporator from freezing.

  Moreover, what utilized the detection result of the temperature sensor provided in the indoor heat exchanger used as a condenser as an opportunity to perform a defrost operation is proposed (for example, refer patent document 2). Based on the detection result of the temperature sensor, the technique described in Patent Document 2 indicates that the refrigerant flow path from the indoor heat exchanger serving as a condenser to the outdoor heat exchanger serving as an evaporator is before frosting. In the case, the defrosting operation is started.

JP 04-372420 A (paragraph [0037]) JP 07-239162 A (Claim 1)

  The technique described in Patent Document 1 realizes prevention of freezing of the evaporator at low cost by obtaining various values by calculation without providing a plurality of temperature sensors in the evaporator. The technique described in Patent Literature 2 uses a detection result of a temperature sensor provided on the condenser side to perform a defrosting operation using a determination result as to whether or not the refrigerant flow passage is before frost formation. Yes.

  However, in the techniques described in Patent Documents 1 and 2, for example, the intermediate temperature of the intermediate portion of the evaporator varies depending on the length of the refrigerant pipe, and therefore, there is a difference between the defrosting operation control or the freeze prevention operation control. there is a possibility.

  The present invention has been made against the background of the above problems, and an object of the present invention is to provide an air conditioner capable of performing defrosting operation control with high accuracy.

  An air conditioner according to the present invention includes a compressor, a flow path switch, an outdoor heat exchanger, an expansion device, a refrigerant circuit in which an indoor heat exchanger is connected via a refrigerant pipe, and a heating operation of the outdoor heat exchanger. Defrosting operation by controlling the refrigerant circuit based on the detection result of the temperature sensor that is provided on the inlet side at the time and detects the inlet temperature that becomes the inlet side of the outdoor heat exchanger during the heating operation The outdoor control device includes a correction value calculation means for calculating a correction value based on the flow rate of the refrigerant flowing through the refrigerant circuit, an inlet temperature detected by the temperature sensor, and a correction value calculation means. The intermediate temperature deriving means for deriving the intermediate temperature of the intermediate portion of the outdoor heat exchanger based on the correction value calculated in step, and the defrosting operation based on the intermediate temperature derived by the intermediate temperature deriving means. Those having a operation mode control unit.

  According to the air conditioner of the present invention, the defrosting operation is performed based on the temperature of the intermediate portion of the evaporator derived based on the flow rate of the refrigerant flowing through the refrigerant pipe. Therefore, the defrosting operation control can be performed with high accuracy.

It is the schematic which shows Embodiment 1 of the air conditioner 1 of this invention. It is a functional block diagram which shows Embodiment 1 of the outdoor control apparatus 63. FIG. It is a figure which shows correlation with piping length, pressure loss (DELTA) P, and refrigerant | coolant circulation flow rate Gr. It is a figure which shows the correspondence of refrigerant | coolant circulation flow rate Gr and correction value (DELTA) T. 3 is a flowchart illustrating an operation example of defrosting operation control according to the first embodiment. It is a functional block diagram which shows Embodiment 2 of the outdoor control apparatus 63. It is a figure which shows the correspondence of the frequency fz of the compressor 21, and correction value (DELTA) T. 6 is a flowchart illustrating an operation example of defrosting operation control according to the second embodiment.

Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing Embodiment 1 of an air conditioner 1 of the present invention. The air conditioner 1 is for air conditioning an air-conditioning target space, and includes an outdoor unit 11 and an indoor unit 13, and the outdoor unit 11 and the indoor unit 13 are connected via a liquid side extension pipe 53 and a gas side extension pipe 55. Connected.

  The outdoor unit 11 includes a compressor 21, a flow path switch 22, an outdoor heat exchanger 23, an expansion device 24, an outdoor blower 31, a liquid side extension pipe connection valve 41, a gas side extension pipe connection valve 43, and a temperature sensor 61. The outdoor control device 63 is provided. The indoor unit 13 includes an indoor heat exchanger 25 and an indoor blower 33. The air conditioner 1 also includes a refrigerant circuit in which a compressor 21, a flow path switch 22, an outdoor heat exchanger 23, an expansion device 24, and an indoor heat exchanger 25 are connected via a refrigerant pipe 51. A refrigeration cycle is formed by circulating the refrigerant in the interior.

  The compressor 21 is formed using a known technique such as a scroll type or a rotary type, for example, and compresses and discharges the refrigerant. The flow path switch 22 is, for example, a four-way valve, and switches the flow path direction of the refrigerant. The flow path switch 22 forms, for example, a refrigerant circuit that connects the discharge side of the compressor 21 and the indoor heat exchanger 25 during heating operation, and connects the suction side of the compressor 21 and the outdoor heat exchanger 23. On the other hand, the flow path switch 22 connects the discharge side of the compressor 21 and the outdoor heat exchanger 23 during the cooling operation, and forms a refrigerant circuit that connects the suction side of the compressor 21 and the indoor heat exchanger 25. .

  The outdoor heat exchanger 23 is formed of, for example, a fin tube, and functions as an evaporator during heating operation and functions as a condenser during cooling operation. The outdoor blower 31 supplies air to the outdoor heat exchanger 23 by rotating an outdoor fan. The indoor heat exchanger 25 is formed of, for example, a fin tube, and functions as a condenser during heating operation and functions as an evaporator during cooling operation. The indoor blower 33 supplies air to the indoor heat exchanger 25 by rotating the indoor fan. The expansion device 24 is formed of, for example, an electronic expansion valve, and adjusts the flow rate of the refrigerant flowing through the refrigerant pipe 51 by adjusting the opening degree.

  The air conditioner 1 further includes a temperature sensor 61 and an outdoor control device 63. The temperature sensor 61 is provided at a location on the inlet side of the outdoor heat exchanger 23 during the heating operation, and supplies the detection result of the inlet temperature Tin to the outdoor control device 63. That is, the temperature sensor 61 is provided in a portion where the outdoor heat exchanger 23 has the lowest temperature during the heating operation.

  The outdoor control device 63 controls the drive of the compressor 21, the flow path switching device 22, the expansion device 24, and the outdoor blower 31. The outdoor control device 63 may control the driving of the indoor blower 33. The outdoor control device 63 acquires the frequency fz from the compressor 21 and the detection result of the temperature sensor 61.

  Next, the details of the outdoor control device 63 will be described with reference to FIGS. FIG. 2 is a functional block diagram showing the first embodiment of the outdoor control device 63. The functional configuration of the outdoor control device 63 in FIG. 2 is constructed by executing a program on hardware such as a microcomputer and a computer. The outdoor control device 63 includes an operation mode control means 71, a correction value calculation means 73, an intermediate temperature derivation means 75, and an intermediate temperature determination means 77, and controls the refrigeration cycle of the refrigerant circuit.

  The operation mode control means 71 changes the operation mode based on the operation command from the indoor unit 13 and performs air conditioning control. Specifically, when the operation command from the indoor unit 13 is the cooling operation, the operation mode control unit 71 changes the operation mode to the cooling operation, and sends the control command related to the cooling operation to the compressor 21, the flow path switch 22, Supply to the expansion device 24 and the outdoor blower 31. In addition, when the operation command from the indoor unit 13 is the heating operation, the operation mode control means 71 changes the operation mode to the heating operation, and the control command related to the heating operation to the compressor 21, the flow path switching device 22, and the expansion device 24. , Supplied to the outdoor blower 31.

  More specifically, when the operation command from the indoor unit 13 is the heating operation, the operation mode control unit 71 supplies a command for causing the correction value calculation unit 73 to calculate the correction value ΔT, for example, and supplies the correction value calculation unit 73 with the command. A correction value ΔT for correcting the inlet temperature Tin as a detection result of the temperature sensor 61 is calculated. The operation mode control means 71 generates a control command for defrosting operation based on the determination result of the intermediate temperature determination means 77, and supplies the generated control command to the flow path switch 22 and the like.

The correction value calculation means 73 includes a refrigerant circulation flow rate derivation means 81, a correction value setting means 83, and a correction value storage means 85. The refrigerant circulation flow rate deriving unit 81 derives the refrigerant circulation flow rate Gr [kg / h] that depends on the frequency fz of the compressor 21, for example, during heating operation. Specifically, the refrigerant circulation flow rate deriving unit 81 includes the stroke volume vst [cc] of the compressor 21, the frequency fz [rps] of the compressor 21, the refrigerant gas density ρ [kg / m ³ ], and the volume efficiency ηv [ The refrigerant circulation flow rate Gr [kg / h] is derived by applying the dimensionless number to the following equation (1).

  The refrigerant circulation flow rate Gr will be specifically described with reference to FIG. FIG. 3 is a diagram showing a correlation among the pipe length, the pressure loss ΔP, and the refrigerant circulation flow rate Gr. As shown in FIG. 3, the amount of the pressure loss ΔP increases in proportion to the pipe length, and the slope, which is the rate of change between the pipe length and the pressure loss ΔP, changes according to the refrigerant circulation flow rate Gr. Therefore, the pressure loss ΔP is determined according to the pipe length, and the refrigerant circulation flow rate Gr is determined according to the pressure loss ΔP. Therefore, since the pressure loss ΔP and the refrigerant circulation flow rate Gr have a correlation, the pressure loss ΔP can also be obtained according to the refrigerant circulation flow rate Gr.

  In addition, the refrigerant state during the heating operation is a wet saturated vapor state surrounded by a saturated liquid line and a saturated vapor line when represented by a ph diagram (not shown). In such a state, if the pressure (temperature) is determined, the temperature (pressure) is determined, and if the pressure (temperature) changes, the temperature (pressure) also changes. Accordingly, since the pressure and the temperature have a correlation, the correction value ΔT can be derived from the pressure loss ΔP by acquiring the correspondence between the pressure loss ΔP and the temperature in advance. For example, as shown in FIG. 4, the correspondence relationship between the refrigerant circulation flow rate Gr and the correction value ΔT is stored in the correction value storage unit 85. FIG. 4 is a diagram illustrating a correspondence relationship between the refrigerant circulation flow rate Gr and the correction value ΔT. As shown in FIG. 4, the refrigerant circulation flow rate Gr is divided into multiple stages, and a correction value ΔT is associated with each stage. That is, since the length of the pipe varies depending on the installation location or the like, the accuracy of the defrosting operation control is improved if the correction value ΔT is set accordingly.

  For example, the correction value setting unit 83 is based on the refrigerant circulation flow rate Gr derived by the refrigerant circulation flow rate deriving unit 81 and the correspondence table of the refrigerant circulation flow rate Gr and the correction value ΔT stored in the correction value storage unit 85. The correction value ΔT is obtained.

  The intermediate temperature deriving means 75 derives the intermediate temperature Tm by adding the correction value ΔT to the inlet temperature Tin detected by the temperature sensor 61. That is, the intermediate temperature deriving unit 79 derives the intermediate temperature Tm of the intermediate portion of the outdoor heat exchanger 23 based on the correction value ΔT and the inlet temperature Tin that becomes the inlet side of the outdoor heat exchanger 23 during the heating operation. The derivation result is supplied to the intermediate temperature determination means 77.

  The intermediate temperature determination means 77 determines whether or not to start the defrosting operation based on the intermediate temperature Tm of the intermediate portion of the outdoor heat exchanger 23 and a preset threshold value Ta, and the determination result is an operation mode control means. 71 is supplied.

  Here, the preset threshold Ta is used as an index indicating that the refrigerant flow path of the outdoor heat exchanger 23 that functions as an evaporator during heating operation is before frosting, for example, by performing actual machine operation in advance. Yes. The threshold value Ta may be set to, for example, −2.0 to −3.0 ° C.

  If the intermediate temperature Tm is equal to or less than a preset threshold Ta, the operation mode control means 71 switches the flow path switch 22 to the state during the cooling operation, and connects the discharge side of the compressor 21 and the outdoor heat exchanger 23. Defrosting operation control is performed by connecting and supplying the outdoor heat exchanger 23 with a high-temperature and high-pressure refrigerant. The operation mode control means 71 does not perform the defrosting operation control if the intermediate temperature Tm is larger than a preset threshold value Ta.

  FIG. 5 is a flowchart illustrating an operation example of the defrosting operation control according to the first embodiment. It is determined whether or not there is an operation command from the indoor unit 13 in the operation mode control means 71. If there is an operation command from the indoor unit 13 (ST1 YES), the operation mode control means 71 changes the operation mode (ST2). On the other hand, when there is no operation command from the indoor unit 13 in the operation mode control means 71 (ST1 NO), the process returns to ST1.

  If the operation mode control means 71 is a heating operation (ST3 YES), the compressor 21 is started to operate (ST4), and it is determined whether or not a certain time has passed (ST5). When a fixed time has elapsed in the operation mode control means 71 (ST5 YES), the refrigerant circulation flow rate deriving means 81 derives the refrigerant circulation flow rate Gr (ST6), the correction value setting means 83 selects the correction value ΔT (ST7), The intermediate temperature deriving means 75 acquires the inlet temperature Tin of the outdoor heat exchanger 23 (ST8), and the intermediate temperature deriving means 75 derives the intermediate temperature Tm (ST9). In intermediate temperature determining means 77, it is determined whether or not intermediate temperature Tm is equal to or lower than threshold value Ta (ST10). When the intermediate temperature determination unit 77 determines that the intermediate temperature Tm is equal to or lower than the threshold Ta (ST10 YES), the operation mode control unit 71 changes the operation mode to defrosting operation and switches the flow path switch 22 (ST11), thereby defrosting operation. Is started and defrosting operation is performed (ST12). When the intermediate temperature determination unit 77 determines that the intermediate temperature Tm is higher than the threshold value Ta (ST10 NO), the above-described example process is repeated from the refrigerant circulation flow rate derivation unit 81 (ST6 to ST10).

  When the operation mode control means 71 is not in the heating operation (ST3 NO), for example, when a cooling command arrives, the cooling operation is performed.

  From the above description, the correction value ΔT is derived based on the refrigerant circulation flow rate Gr of the refrigerant pipe 51, and the defrosting operation is started by comparing the intermediate temperature Tm of the intermediate portion of the evaporator corrected with the correction value ΔT with the threshold value Ta. It is said. As a result, the defrosting operation control in consideration of the pressure loss ΔP of the refrigerant flow path is performed, so that the defrosting operation control can be performed with high accuracy.

  On the other hand, since the intermediate temperature Tm is corrected including the pressure loss ΔP from the inlet side of the evaporator to the intermediate portion, the intermediate temperature Tm is an accurate value. Since it is determined whether or not the defrosting operation control is to be performed based on such an accurate intermediate temperature Tm, the defrosting operation control can be accurately started. Thereby, since useless defrosting operation control can be avoided, it is also possible to reduce power consumption.

  Further, regarding the defrosting operation control, only one temperature sensor 61 is provided in the outdoor heat exchanger 23, so that it is not necessary to provide a plurality of temperature sensors 61 in the outdoor heat exchanger 23. Therefore, defrosting operation control can be realized at low cost.

Embodiment 2. FIG.
In the first embodiment, the case where the correction value ΔT is obtained from the refrigerant circulation flow rate Gr has been described. In the second embodiment, for example, the correction value ΔT is derived based on the correspondence between the frequency fz of the compressor 21 and the correction value ΔT. Will be described. In the second embodiment, items not particularly described are the same as those in the first embodiment, and the same functions and the like are described using the same reference numerals.

  FIG. 6 is a functional block diagram illustrating the second embodiment of the outdoor control device 63. The correction value storage means 95 corrects the correction value ΔT of the intermediate temperature Tm at the intermediate portion of the outdoor heat exchanger 23 as the pressure loss ΔP of the refrigerant pipe 51 increases as the frequency fz of the compressor 21 increases. A correspondence table for increasing the amount is stored. FIG. 7 is a diagram illustrating a correspondence relationship between the frequency fz of the compressor 21 and the correction value ΔT. As shown in FIG. 7, the frequency fz of the compressor 21 is divided into multiple stages, and a correction value ΔT is associated with each stage.

  Specifically, as shown in FIG. 7, for example, when the frequency fz is 30 or less, the correction value ΔT is set to −0.5 ° C., and when the frequency fz is larger than 30 and smaller than 60, The correction value ΔT is set to −1.0, and when the frequency fz is 60 or more, the correction value ΔT is set to −1.5. For such a correction value ΔT, it is only necessary to actually measure the correction value ΔT corresponding to the change in the frequency fz by performing the actual machine operation in advance in the evaluation stage. For example, during heating operation, the correction value ΔT is measured by providing the temperature sensors 61 at locations where the minimum temperature of the outdoor heat exchanger 23 can be detected and locations where the average temperature of the outdoor heat exchanger 23 can be detected. It may be left. In the above example, the number of steps is three, but the correction value ΔT can be made finer by increasing the number of steps.

  The correction value setting means 93 selects a plurality of correction values ΔT stepwise according to the frequency fz of the compressor 21. FIG. 8 is a flowchart illustrating an operation example of the defrosting operation control according to the second embodiment. FIG. 8 is the same step as FIG. 5 except that there is no step for deriving the refrigerant circulation flow rate Gr, and therefore the description thereof is omitted.

  From the above description, since it is not necessary to derive the refrigerant circulation flow rate Gr by having a correspondence relationship between the frequency fz of the compressor 21 and the correction value ΔT, the defrosting operation can be started more easily.

  As described above, in Embodiments 1 and 2 of the present invention, the refrigerant in which the compressor 21, the flow path switch 22, the outdoor heat exchanger 23, the expansion device 24, and the indoor heat exchanger 25 are connected via the refrigerant pipe 51. A circuit, a temperature sensor 61 that is provided on the inlet side during the heating operation of the outdoor heat exchanger 23, detects an inlet temperature Tin that becomes the inlet side of the outdoor heat exchanger 23 during the heating operation, and a temperature sensor 61 during the heating operation. And an outdoor control device 63 that performs a defrosting operation by controlling the refrigerant circuit based on the detection result of, and the outdoor control device 63 calculates a correction value ΔT based on the flow rate of the refrigerant flowing through the refrigerant circuit. Based on the calculation means 73, the inlet temperature Tin detected by the temperature sensor 61, and the correction value ΔT calculated by the correction value calculation means 73, the intermediate temperature of the intermediate portion of the outdoor heat exchanger 23 is calculated. An intermediate temperature deriving unit 75 for deriving Tm and an operation mode control unit 71 for performing a defrosting operation based on the intermediate temperature Tm derived by the intermediate temperature deriving unit 75 are provided. Thereby, the intermediate temperature Tm of the intermediate part of the evaporator derived | led-out based on the pressure loss (DELTA) P of the refrigerant | coolant piping 51 is used as the opportunity of defrosting operation control start. Therefore, defrosting operation control can be performed according to the intermediate temperature Tm of the intermediate part of the evaporator. Therefore, defrosting operation control can be performed with high accuracy.

  In Embodiment 1 of the present invention, the correction value ΔT is a negative value and has a correlation with the refrigerant circulation flow rate Gr of the refrigerant circuit, and the refrigerant circulation flow rate Gr of the refrigerant circuit increases. As the value increases, the absolute value of the correction value ΔT increases. Thereby, the correction value ΔT of the intermediate temperature Tm of the intermediate portion of the outdoor heat exchanger 23 can be increased according to the increase of the refrigerant circulation flow rate Gr. Therefore, the correction value ΔT can be set in consideration of the pressure loss ΔP.

  Further, in the first embodiment of the present invention, the correction value calculation means 73 has a table of correlation between the refrigerant circulation flow rate Gr and the correction value ΔT. Thereby, the correction value ΔT can be easily obtained from the refrigerant circulation flow rate Gr.

  In the first embodiment of the present invention, the correction value calculation means 73 divides the refrigerant circulation flow rate Gr into multiple stages and obtains a correction value ΔT corresponding to the refrigerant circulation flow rate Gr divided into multiple stages. As a result, the correction value ΔT can be set stepwise in accordance with the refrigerant circulation flow rate Gr.

  In the second embodiment of the present invention, the correction value calculation means 73 uses the frequency fz of the compressor 21 as the refrigerant circulation flow rate Gr. Thereby, the correction value ΔT can be easily set.

  Moreover, in Embodiment 2 of this invention, the correction value calculating means 73 has a table of correlation between the frequency fz of the compressor 21 and the correction value ΔT. Thereby, the correction value ΔT can be easily obtained from the frequency fz of the compressor 21.

  In the second embodiment of the present invention, the correction value calculation means 73 divides the frequency fz of the compressor 21 into multiple stages and obtains a correction value ΔT corresponding to the frequency fz of the compressor 21 divided into multiple stages. It is. As a result, the correction value ΔT can be set stepwise in accordance with the frequency fz of the compressor 21.

  In the first and second embodiments of the present invention, the operation mode control means 71 starts the defrosting operation based on the comparison result between the intermediate temperature Tm and a preset threshold value Ta. When Tm is equal to or lower than the threshold value Ta, the defrosting operation is started. When the intermediate temperature Tm exceeds the threshold value Ta, the defrosting operation is not started. Thereby, defrosting operation can be started with high accuracy.

  The embodiment of the present invention is not limited to the first and second embodiments. In the above description, the defrosting control method has been described as an example in which the reverse flow defrost method is used in which frost is melted by reversing the flow direction of the refrigerant in the refrigerant circuit and flowing the hot gas refrigerant to the evaporator. It is not limited. For example, when the internal temperature is 0 ° C. or lower, a method of heating with a heater attached to the evaporator may be used. Moreover, when the internal temperature exceeds 0 degreeC, the flow of the refrigerant | coolant in the refrigerant | coolant piping of an evaporator may be stopped, and the off-cycle defrost system which melt | dissolves frost by operating only the outdoor air blower 31 may be used.

  DESCRIPTION OF SYMBOLS 1 Air conditioner, 11 Outdoor unit, 13 Indoor unit, 21 Compressor, 22 Flow path switch, 23 Outdoor heat exchanger, 24 Throttle device, 25 Indoor heat exchanger, 31 Outdoor blower, 33 Indoor blower, 41 Liquid side Extension pipe connection valve, 43 Gas side extension pipe connection valve, 51 Refrigerant pipe, 53 Liquid side extension pipe, 55 Gas side extension pipe, 61 Temperature sensor, 63 Outdoor control device, 71 Operation mode control means, 73 Correction value calculation Means, 75 intermediate temperature deriving means, 77 intermediate temperature determining means, 81 refrigerant circulation flow rate deriving means, 83, 93 correction value setting means, 85, 95 correction value storage means.

Claims (8)

A refrigerant circuit in which a compressor, a flow path switch, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger are connected via a refrigerant pipe;
A temperature sensor that is provided on the inlet side during heating operation of the outdoor heat exchanger, and detects an inlet temperature that becomes the inlet side of the outdoor heat exchanger during the heating operation;
An outdoor control device that performs a defrosting operation by controlling the refrigerant circuit based on a detection result of the temperature sensor during the heating operation,
The outdoor control device includes:
Correction value calculating means for calculating a correction value based on the flow rate of the refrigerant flowing through the refrigerant circuit;
Intermediate temperature deriving means for deriving an intermediate temperature of the intermediate portion of the outdoor heat exchanger based on the inlet temperature detected by the temperature sensor and the correction value calculated by the correction value calculating means;
An air conditioner comprising: an operation mode control unit that performs a defrosting operation based on the intermediate temperature derived by the intermediate temperature deriving unit.   The correction value is a negative value and has a correlation with the refrigerant circulation flow rate of the refrigerant circuit, and the absolute value of the correction value increases as the refrigerant circulation flow rate of the refrigerant circuit increases. The air conditioner according to claim 1, wherein the air conditioner is one.   The air conditioner according to claim 2, wherein the correction value calculation means includes a correlation table between the refrigerant circulation flow rate and the correction value.   The air conditioner according to claim 2 or 3, wherein the correction value calculation means divides the refrigerant circulation flow rate into a plurality of stages and obtains the correction value based on the refrigerant circulation flow rate divided into a plurality of stages.   The air conditioner according to any one of claims 2 to 4, wherein the correction value calculation means uses a frequency of the compressor as the refrigerant circulation flow rate.   6. The air conditioner according to claim 5, wherein the correction value calculation means has a table of correlation between the frequency of the compressor and the correction value.   The air conditioner according to claim 5 or 6, wherein the correction value calculation means divides the frequency of the compressor into a plurality of stages and obtains the correction value based on the frequency of the compressor divided into a plurality of stages. The operation mode control means includes
The defrosting operation is started based on a comparison result between the intermediate temperature and a preset threshold value,
The defrosting operation is started when the intermediate temperature is equal to or lower than the threshold value, and the defrosting operation is not started when the intermediate temperature exceeds the threshold value. Air conditioner as described in.

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