JP5447499B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus having a refrigeration circuit including an evaporator.

  2. Description of the Related Art Conventionally, there is known an air conditioner to which a refrigeration apparatus that includes a refrigeration circuit that circulates a refrigerant and that transfers heat between an indoor heat exchanger and an outdoor heat exchanger of the refrigeration circuit is applied. In such an air conditioner, in order to perform appropriate heat exchange with an indoor heat exchanger or an outdoor heat exchanger, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-27066), an evaporator The degree of superheat is controlled to control the degree of superheat of the refrigerant at the outlet.

  By the way, in recent years, there is an increasing demand for energy saving that suppresses power consumption of air conditioners. For example, as one of measures for that purpose, there is a low differential pressure where the difference between the high pressure and the low pressure in the refrigeration cycle is small. In such an air conditioner, when the operation of raising the evaporation temperature is performed when the refrigerant charging amount is large and the outside air temperature is low, the refrigerant is supercooled in front of the indoor heat exchanger functioning as an evaporator. Sometimes. Thus, when a supercooled state occurs in the indoor heat exchanger, there arises a problem that the degree of superheat of the indoor heat exchanger cannot be controlled.

  An object of the present invention is to appropriately perform superheat degree control of a refrigeration apparatus in which a refrigerant is likely to be in a supercooled state before an evaporator.

A refrigeration apparatus according to a first aspect of the present invention is a refrigeration apparatus in which a compressor, a radiator, and an evaporator are connected in order to form a refrigerant circuit in which refrigerant circulates, and is provided on the inflow side of the evaporator. Expansion mechanism for controlling expansion of the refrigerant flowing into the evaporator based on at least one of the high pressure target value of the refrigerant circuit, the low pressure target value of the refrigerant circuit, and the superheat degree target value on the outflow side of the evaporator And a detector for detecting the supercooled state of the refrigerant on the inflow side of the evaporator, and a high pressure when it is determined that the refrigerant on the inflow side of the evaporator is in the supercooled state based on the detection result of the detector. A control unit capable of performing at least one predetermined setting change among a setting change for raising the target value, a setting change for lowering the low pressure target value, and a setting change for raising the superheat degree target value.

  In the refrigeration apparatus according to the first aspect, when it is determined that the refrigerant on the inflow side of the evaporator is in a supercooled state, among the setting changes that increase the high pressure target value, decrease the low pressure target value, and increase the superheat degree target value Since it is possible to avoid the situation where the superheat degree control of the evaporator cannot be performed by changing at least one of the above settings, it is possible to appropriately control the superheat degree of the evaporator.

  In the refrigeration apparatus according to the second aspect of the present invention, in the refrigeration apparatus according to the first aspect, the control unit restores the predetermined setting change when the supercooling state is resolved after performing the predetermined setting change. It is configured as follows.

  In the refrigeration apparatus according to the third aspect of the present invention, in the refrigeration apparatus according to the third aspect, the control unit changes the value and the predetermined setting change when it is determined that the supercooling state is reached when the predetermined setting change is performed. A margin for preventing hunting is provided between the value at which it is determined that the supercooled state has been removed when returning to the original state.

The refrigeration apparatus according to the fourth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects, wherein the evaporator is a use-side heat exchanger, and the control unit uses the detection result of the detector. Based on this, when it is determined that the refrigerant on the inflow side of the use side heat exchanger is in a supercooled state, at least one of a setting change that lowers the low pressure target value and a setting change that increases the superheat degree target value can be performed.

In the refrigeration apparatus according to the fourth aspect , when it is determined that the refrigerant on the inflow side of the use-side heat exchanger is in the supercooled state, of the setting change that lowers the low pressure target value and the setting change that increases the superheat degree target value It is possible to avoid a supercooled state by performing at least one of them, and because the amount of refrigerant is large, it is sufficient when the refrigerant tends to be supercooled in front of the use side heat exchanger functioning as an evaporator Is possible.

The refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to the fourth aspect, wherein the detector is a first detector for detecting the pressure saturation temperature on the inflow side of the use side heat exchanger and the use side heat. A second detector for detecting the temperature of the refrigerant on the inflow side of the exchanger, or a third detector for detecting the temperature of the refrigerant on the inflow side of the expansion mechanism and the first detector, Whether the refrigerant on the inflow side of the use side heat exchanger is in a supercooled state based on the comparison of the detection results of the first detector and the second detector or the comparison of the detection results of the first detector and the third detector. It can be determined whether or not.

In the refrigeration apparatus according to the fifth aspect, whether the refrigerant on the inflow side of the use side heat exchanger is in a supercooled state is determined by comparing the detection results of the first detector and the second detector or by the first detector. Therefore, even if the refrigerant on the inflow side of the use side heat exchanger is supercooled, it is possible to accurately determine the supercooled state.

The refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to the fifth aspect , wherein the third detector is a liquid pipe temperature sensor provided on the outflow side of the radiator, and the control unit Using the temperature obtained by subtracting the correction value corresponding to the heat loss from the sensor mounting position to the expansion mechanism from the detection temperature of the liquid pipe temperature sensor as the refrigerant temperature on the inflow side of the expansion mechanism, the inflow of the use side heat exchanger It can be determined whether or not the side refrigerant is in a supercooled state.

In the refrigeration apparatus according to the sixth aspect , a conventional heat source side liquid tube temperature sensor can be used to determine whether or not the refrigerant on the inflow side of the use side heat exchanger is in a supercooled state.

In the refrigeration apparatus according to the seventh aspect of the present invention, in the refrigeration apparatus according to the fifth aspect or the sixth aspect , the first detector is an intake pressure sensor that detects the pressure on the intake side of the compressor, and the control unit includes: The pressure saturation temperature can be calculated from the pressure detected by the suction pressure sensor.

In the refrigeration apparatus according to the seventh aspect , since the control unit can calculate the pressure saturation temperature from the pressure detected by the suction pressure sensor, a conventional suction pressure sensor can be used.

In the refrigeration apparatus according to the first aspect , the second aspect, or the third aspect, it is possible to appropriately control the superheat degree of the evaporator while avoiding the situation where the superheat degree control of the evaporator cannot be performed. It is possible to appropriately perform the superheat degree control of the refrigeration apparatus in which the refrigerant is likely to be in a supercooled state before this.

In the refrigeration apparatus according to the fourth aspect, it is possible to appropriately control the superheat degree of the use side heat exchanger while avoiding the situation where the superheat degree control of the use side heat exchanger cannot be performed. Therefore, it is possible to appropriately perform superheat degree control of the refrigeration apparatus in which the refrigerant is likely to be in a supercooled state.

In the refrigeration apparatus according to the fifth aspect , the supercooling state can be accurately determined, and the superheat degree control of the refrigeration apparatus in which the refrigerant is supercooled before the evaporator can be appropriately performed.

In the refrigeration apparatus according to the sixth aspect , since a conventional heat source side liquid pipe temperature sensor can be used, an increase in cost can be suppressed.

In the refrigeration apparatus according to the seventh aspect , since a conventional suction pressure sensor can be used, an increase in cost can be suppressed.

The figure which shows the refrigerant | coolant piping system of the air conditioning apparatus containing the freezing apparatus which concerns on one Embodiment. The block diagram which shows the control system of the air conditioning apparatus of FIG. The graph for demonstrating operation | movement of a freezing circuit.

(1) Whole structure of air conditioning apparatus FIG. 1: has shown the refrigerant | coolant piping system | strain of the air conditioning apparatus containing the freezing apparatus which concerns on one Embodiment of this invention. The air conditioner 1 is a distributed type air conditioner using a refrigerant piping system, and is an apparatus used for cooling and heating each room in a building by performing a vapor compression refrigeration cycle operation. The air conditioner 1 includes an air conditioner outdoor unit 2 as a heat source unit, a plurality of air conditioner indoor units 4 (in FIG. 1, two units of an air conditioner indoor unit 4a and an air conditioner indoor unit 4b), and an air conditioner outdoor unit. 1 and the 2nd refrigerant | coolant communication pipe | tube 7 as a refrigerant | coolant communication pipe | tube which connects 2 and the air-conditioning indoor unit 4 are provided.

  The refrigeration apparatus 10 of the air conditioner 1 is configured by connecting an air conditioning outdoor unit 2, an air conditioning indoor unit 4, and refrigerant communication pipes 6 and 7. The refrigerant is sealed in the refrigeration apparatus 10, and as described later, the refrigerant is compressed, cooled, depressurized, heated and evaporated, and then compressed again. It has become. As the refrigerant, for example, one selected from R410A, R407C, R22, R134a, carbon dioxide, and the like is used.

(2) Detailed configuration of air conditioner (2-1) Air-conditioning indoor unit The air-conditioning indoor unit is installed by being embedded or suspended in the ceiling of a room such as a building, or by hanging on a wall surface of the room. The air conditioning indoor unit 4 is connected to the air conditioning outdoor unit 2 via the refrigerant communication pipes 6 and 7 and constitutes a part of the refrigeration apparatus 10.

  Next, the configuration of the air conditioning indoor unit 4 will be described. In FIG. 1, two air conditioning indoor units 4a and 4b are shown as the air conditioning indoor unit 4. However, since each of the air conditioning indoor units 4 has almost the same configuration, only the configuration of the air conditioning indoor unit 4a is shown here. Will be explained.

  The air conditioning indoor unit 4 a has an indoor main refrigerant circuit 10 a that constitutes a part of the refrigeration apparatus 10. The indoor main refrigerant circuit 10a mainly includes an indoor expansion valve 41 that is a decompressor and an indoor heat exchanger 42 that is a use-side heat exchanger.

  The indoor expansion valve 41 is a mechanism for reducing the pressure of the refrigerant, and is an electric valve capable of adjusting the opening degree. The indoor expansion valve 41 has one end connected to the first refrigerant communication pipe 6 and the other end connected to the indoor heat exchanger 42.

  The indoor heat exchanger 42 is, for example, a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and functions as a refrigerant evaporator during cooling operation to cool indoor air. In the heating operation, the heat exchanger functions as a refrigerant condenser and heats indoor air. The indoor heat exchanger 42 has one end connected to the indoor expansion valve 41 and the other end connected to the second refrigerant communication tube 7.

  The air conditioning indoor unit 4a includes an indoor fan 43 for sucking indoor air into the unit and supplying the indoor air again, and exchanges heat between the indoor air and the refrigerant flowing through the indoor heat exchanger 42. . The indoor fan 43 is a fan capable of changing the air volume of air supplied to the indoor heat exchanger 42, and is rotationally driven by an indoor fan motor 43a including a DC fan motor. In the indoor fan 43, for example, a centrifugal fan or a multi-blade fan is driven by the indoor fan motor 43a in order to send air to the indoor heat exchanger.

  The air conditioning indoor unit 4a is provided with various sensors. Specifically, an indoor liquid pipe temperature sensor 44 and an indoor gas pipe temperature sensor 45 each including a thermistor are provided, and the temperature of the refrigerant is measured from the temperature of the refrigerant pipe adjacent to the indoor heat exchanger 42. Moreover, the indoor temperature sensor 46 is provided, This indoor temperature sensor 46 detects the temperature of the indoor air inhaled by the air-conditioning indoor unit 4 before heat exchange is performed. Furthermore, the air conditioning indoor unit 4a has an indoor control device 47 that controls the operation of each part constituting the air conditioning indoor unit 4a. The indoor control device 47 has a microcomputer, a memory, and the like provided for controlling the air conditioning indoor unit 4a, and a remote controller (not shown) for individually operating the air conditioning indoor unit 4a. Control signals and the like are exchanged between them, and control signals and the like are exchanged with the outdoor control device 30 of the air conditioner outdoor unit 2 described later via the transmission line 8a.

(2-2) Air-conditioning outdoor unit The air-conditioning outdoor unit 2 is installed outside a building or the like, and is connected to the air-conditioning indoor units 4a and 4b via the first refrigerant communication pipe 6 and the second refrigerant communication pipe 7. Yes. The air conditioning outdoor unit 2 includes an outdoor main refrigerant circuit 10 c that constitutes a part of the refrigeration apparatus 10 and a supercooling refrigerant flow path 61 that branches from the refrigeration apparatus 10.

(2-2-1) Outdoor Main Refrigerant Circuit The outdoor main refrigerant circuit 10c mainly includes the compressor 21, the switching mechanism 22, the outdoor heat exchanger 23, the outdoor first expansion valve 25, and liquid gas heat. It has an exchanger 27, a liquid side closing valve 28 a, a gas side closing valve 28 b, and an accumulator 29. The outdoor main refrigerant circuit 10c mainly includes a compressor 21, a switching mechanism 22, an outdoor heat exchanger 23 as a heat source side heat exchanger, and an outdoor first expansion as a second shut-off mechanism or a heat source side expansion mechanism. It has a valve 25, a liquid gas heat exchanger 27 as a temperature adjusting mechanism, a liquid side closing valve 28a as a first shut-off mechanism, and a gas side closing valve 28b.

  The compressor 21 is a hermetic compressor driven by a compressor motor 21a. The rotation speed of the compressor motor 21a is controlled by, for example, an inverter, and the compressor 21 is configured to be able to vary the operating capacity.

  The switching mechanism 22 is a mechanism for switching the direction of the refrigerant flow. During the cooling operation, the outdoor heat exchanger 23 functions as a radiator for the refrigerant compressed by the compressor 21, and the indoor heat exchanger 42 functions as an evaporator for the refrigerant cooled in the outdoor heat exchanger 23. For this purpose, the switching mechanism 22 connects the refrigerant pipe on the discharge side of the compressor 21 and one end of the outdoor heat exchanger 23, and also connects the compressor suction side pipe 29a (including the accumulator 29) and the gas side closing valve 28b. (See the solid line of the switching mechanism 22 in FIG. 1). Further, the switching mechanism 22 causes the indoor heat exchanger 42 to function as a radiator for the refrigerant compressed by the compressor 21 during the heating operation, and the outdoor heat exchanger 23 is cooled by the indoor heat exchanger 42. To function as an evaporator. For this purpose, the switching mechanism 22 connects the refrigerant pipe on the discharge side of the compressor 21 and the gas side shut-off valve 28b, and connects the compressor suction side pipe 29a and one end of the outdoor heat exchanger 23 (FIG. 1 (see the broken line of the switching mechanism 22). The switching mechanism 22 is, for example, a four-way switching valve.

  The outdoor heat exchanger 23 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, one end of which is connected to the switching mechanism 22 and the other end of the outdoor heat exchanger 23. The first expansion valve 25 is connected.

  The air conditioner outdoor unit 2 has an outdoor fan 26 for sucking outdoor air into the unit and discharging it to the outdoor again. The outdoor fan 26 exchanges heat between the outdoor air and the refrigerant flowing through the outdoor heat exchanger 23.

  The outdoor first expansion valve 25 is a mechanism for decompressing the refrigerant in the refrigeration apparatus 10, and is an electric valve capable of adjusting the opening degree. The outdoor first expansion valve 25 is configured to adjust the pressure, flow rate, and the like of the refrigerant flowing in the outdoor main refrigerant circuit 10c in the outdoor heat exchanger 23 in the refrigerant flow direction in the refrigeration apparatus 10 during the cooling operation. It is also possible to block the passage of the refrigerant by being arranged on the downstream side of the gas and upstream of the liquid gas heat exchanger 27. One end of the outdoor first expansion valve 25 is connected to the outdoor heat exchanger 23, and the other end is connected to the liquid side shut-off valve 28 a via the liquid gas heat exchanger 27, and is connected to the liquid side of the indoor heat exchanger 42. It is connected.

  The air-conditioning outdoor unit 2 has an outdoor fan 26 as a blower fan for sucking outdoor air into the unit and exchanging heat with the refrigerant in the outdoor heat exchanger 23 and then discharging it to the outside. The outdoor fan 26 is a fan capable of changing the air volume supplied to the outdoor heat exchanger 23, and is, for example, a propeller fan driven by a motor 26a composed of a DC fan motor or the like.

  The liquid gas heat exchanger 27 is connected between the outdoor first expansion valve 25 and the liquid side closing valve 28a. The liquid gas heat exchanger 27 is a pipe heat exchanger having a double-pipe structure in which a refrigerant pipe through which the refrigerant condensed in the heat source side heat exchanger flows and a branch pipe 64 described later are brought into contact with each other. The liquid gas heat exchanger 27 includes a refrigerant that flows in the refrigeration apparatus 10 from the outdoor heat exchanger 23 toward the air conditioning indoor unit 4, and a supercooling refrigerant flow path 61 from the outdoor second expansion valve 62 to the compressor suction side pipe 29a. Heat exchange with the refrigerant flowing into the Thereby, the liquid gas heat exchanger 27 further cools the refrigerant condensed in the outdoor heat exchanger 23 during the cooling operation by this heat exchange, and increases the degree of supercooling of the refrigerant toward the air conditioning indoor unit 4.

  The accumulator 29 is disposed in a compressor suction side pipe 29 a between the switching mechanism 22 and the compressor 21.

(2-2-2) Supercooling Refrigerant Channel The supercooling refrigerant channel 61 is a compressor between the switching mechanism 22 and the accumulator 29 via the liquid gas heat exchanger 27 from the outdoor second expansion valve 62. It is comprised with the refrigerant | coolant pipe | tube toward the suction side piping 29a. The outdoor second expansion valve 62 is a mechanism for decompressing the refrigerant in the supercooling refrigerant flow path 61, and is an electric valve capable of adjusting the opening degree. The outdoor second expansion valve 62 is provided in the supercooling refrigerant flow path 61, and in the supercooling refrigerant flow path 61 branches from a pipe connected from the outdoor first expansion valve 25 to the liquid side closing valve 28a to exchange liquid gas heat. It is arranged until the container 27 is entered.

  The liquid gas heat exchanger 27 is provided with a branch pipe 64 as a cooling source. A portion of the refrigeration apparatus 10 excluding the supercooling refrigerant flow path 61 is a main refrigerant circuit. The supercooling refrigerant channel 61 is connected to the main refrigerant circuit so as to return the refrigerant branched between the liquid gas heat exchanger 27 and the outdoor first expansion valve 25 to the suction side of the compressor 21. The refrigerant branched in the supercooling refrigerant passage 61 is decompressed and then introduced into the liquid gas heat exchanger 27. The refrigerant branched in the supercooling refrigerant flow path 61 is subjected to heat exchange with the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valve 41 through the first refrigerant communication pipe 6, and then the suction side of the compressor 21. Returned to

  More specifically, the supercooling refrigerant flow path 61 includes a branch pipe 64, a junction pipe 65, and an outdoor second expansion valve 62. The branch pipe 64 is connected so that a part of the refrigerant sent from the outdoor first expansion valve 25 to the indoor expansion valve 41 is branched from a position between the outdoor heat exchanger 23 and the liquid gas heat exchanger 27. Yes. The junction pipe 65 is connected to the suction side of the compressor 21 so as to return to the suction side of the compressor 21 from the outlet on the supercooling refrigerant flow path side of the liquid gas heat exchanger 27. The outdoor second expansion valve 62 is an electric expansion valve, and functions as a communication pipe expansion mechanism for adjusting the flow rate of the refrigerant flowing through the supercooling refrigerant flow path 61. Thereby, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valve 41 is caused by the refrigerant flowing in the subcooling refrigerant flow path 61 after being depressurized by the outdoor second expansion valve 62 in the liquid gas heat exchanger 27. To be cooled. That is, the capacity control of the liquid gas heat exchanger 27 is performed by adjusting the opening degree of the outdoor second expansion valve 62.

  Further, as described later, the supercooling refrigerant flow path 61 connects a portion of the refrigeration apparatus 10 between the liquid side closing valve 28a and the outdoor first expansion valve 25 and a suction side portion of the compressor 21. It is designed to function as a communication pipe.

  The liquid side shutoff valve 28a and the gas side shutoff valve 28b are valves provided at connection ports with external devices and pipes (specifically, the first refrigerant communication pipe 6 and the second refrigerant communication pipe 7). The liquid side shut-off valve 28a is connected to the liquid gas heat exchanger 27, and the gas side shut-off valve 28b is connected to the switching mechanism 22, thereby blocking the passage of the refrigerant.

(2-2-3) Outdoor Control Device and Various Sensors The air-conditioning outdoor unit 2 has an outdoor control device 30 that controls the operation of each part constituting the air-conditioning outdoor unit 2. The outdoor control device 30 includes a microcomputer provided for controlling the air conditioning outdoor unit 2, a memory, an inverter circuit for controlling the motor 26a, and the like, and the indoor control devices for the air conditioning indoor units 4a and 4b. Control signals and the like can be exchanged with the terminal 47 via the transmission line 8a. That is, the indoor control device 47, the outdoor control device 30, and the transmission line 8a connecting the indoor control devices 47 constitute the air conditioning control device 8 that controls the operation of the entire air conditioner 1.

  The air conditioner outdoor unit 2 is provided with various sensors. The refrigerant pipe on the discharge side of the compressor 21 is provided with a discharge pressure sensor 31 that detects the compressor discharge pressure and a discharge temperature sensor 32 that detects the compressor discharge temperature. The compressor suction side pipe 29a is provided with a suction temperature sensor 34 for detecting the temperature of the gas refrigerant sucked into the compressor 21 and a suction pressure sensor 33 for detecting the compressor suction pressure. The outdoor control device 30 is configured to control the operation capacity of the compressor 21, and is a low pressure target value that is a target value of the suction pressure of the compressor 21 during the cooling operation and a discharge of the compressor 21 during the heating operation. It has a high pressure target value that is a target value of pressure. The operating capacity of the compressor 21 is controlled so that the suction pressure sensor 33 becomes the low pressure target value during the cooling operation, and the operating capacity of the compressor 21 is controlled so that the discharge pressure sensor 31 becomes the high pressure target value during the heating operation. Is done.

  Further, a liquid pipe temperature sensor 35 for detecting the temperature of the refrigerant (that is, the liquid pipe temperature) is provided at the outlet of the liquid gas heat exchanger 27 on the main refrigerant circuit side. An outdoor temperature sensor 36 for detecting the temperature of the outdoor air flowing into the inside (that is, the outdoor temperature) is provided on the outdoor air suction side of the air conditioning outdoor unit 2. From the liquid gas heat exchanger 27 to the low-pressure refrigerant pipe between the switching mechanism 22 and the accumulator 29, a supercooling refrigerant flow of the liquid gas heat exchanger 27 flows into the merge pipe 65 of the supercooling refrigerant flow path 61. A bypass temperature sensor 63 for detecting the temperature of the refrigerant flowing through the roadside outlet is provided. The discharge temperature sensor 32, the suction temperature sensor 34, the liquid pipe temperature sensor 35, the outdoor temperature sensor 36, and the bypass temperature sensor 63 are composed of thermistors.

(2-3) Refrigerant communication pipes The refrigerant communication pipes 6 and 7 are refrigerant pipes constructed on site when the air-conditioning outdoor unit 2 and the air-conditioning indoor unit 4 are installed at the installation location. The first refrigerant communication pipe 6 is connected to the air-conditioning outdoor unit 2 and the air-conditioning indoor units 4a and 4b. During the cooling operation, the liquid refrigerant whose degree of supercooling in the liquid gas heat exchanger 27 is increased to the indoor expansion valve 41. And a refrigerant pipe that sends the liquid refrigerant condensed in the indoor heat exchanger 42 to the outdoor heat exchanger 23 of the air conditioning outdoor unit 2 during heating operation. The second refrigerant communication pipe 7 is connected to the air-conditioning outdoor unit 2 and the air-conditioning indoor units 4a and 4b, and sends the gas refrigerant evaporated in the indoor heat exchanger 42 to the compressor 21 of the air-conditioning outdoor unit 2 during the cooling operation. In the heating operation, the refrigerant pipes send the gas refrigerant compressed in the compressor 21 to the indoor heat exchangers 42 of the air conditioning indoor units 4a and 4b.

(2-4) Air Conditioning Control Device FIG. 2 shows a control block diagram of the air conditioner 1. The air conditioning control device 8 as a control means for performing various operation controls of the air conditioner 1 is configured by an outdoor control device 30 and an indoor control device 47 connected via a transmission line 8a as shown in FIG. The air conditioning control device 8 receives the detection signals of the various sensors 31 to 36, 44 to 46, 63, and controls the various devices 21, 22, 25, 26, 41, 43, 62 based on these detection signals and the like.

(3) Operation of Air Conditioner Next, the basic operation of the air conditioner 1 according to the present embodiment will be described. Note that control in various operations described below is performed by the air conditioning control device 8.

(3-1) Cooling operation In an air conditioner operating at a low differential pressure where the difference between the high pressure and the low pressure in the refrigeration cycle is small, for example, an operation that raises the evaporation temperature when the refrigerant charge amount is large and the outside air temperature is low As a result, the refrigerant may be supercooled before the indoor heat exchanger 42 functioning as an evaporator. In the following description, the operation when the subcooling state is not in front of the indoor heat exchanger 42 is referred to as a normal cooling operation, and the operation when the subcooling state is referred to as an abnormal cooling operation. Both will be described separately.

(3-1-1) Cooling operation at normal time During the cooling operation, the switching mechanism 22 is in the state shown by the solid line in FIG. 1, that is, the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23, In addition, the suction side of the compressor 21 is connected to the gas side of the indoor heat exchanger 42 via the gas side closing valve 28 b and the second refrigerant communication pipe 7. During the cooling operation, the outdoor first expansion valve 25 is fully opened, and the liquid side closing valve 28a and the gas side closing valve 28b are opened.

  The opening degree of each indoor expansion valve 41 is adjusted so that the superheat degree of the refrigerant at the outlet of the indoor heat exchanger 42 (that is, the gas side of the indoor heat exchanger 42) becomes constant at the first superheat degree target value Tsh1. It is like that. For example, in FIG. 3, the point C of the pressure P1 is the inflow side of the indoor expansion valve 41, and the point B of the pressure P2 is the outflow side of the indoor expansion valve 41. The degree of superheat of the refrigerant at the outlet of each indoor heat exchanger 42 is obtained by subtracting the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44 from the refrigerant temperature Th1 detected by the indoor gas pipe temperature sensor 45 in the indoor control device 47. Is detected by

  At this time, the fact that the subcooling state is not reached before the indoor heat exchanger 42 is that the indoor unit liquid pipe pressure saturation temperature Tein is detected from the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44 in the indoor control device 47. Is determined not to be high (Tein ≦ Th2). The indoor unit liquid pipe pressure saturation temperature Tein is obtained, for example, by converting the suction pressure LP of the compressor 21 detected by the suction pressure sensor 33 into a saturation temperature corresponding to the evaporation temperature Te.

  The opening degree of the outdoor second expansion valve 62 is adjusted so that the superheat degree of the refrigerant at the outlet of the liquid gas heat exchanger 27 on the supercooling refrigerant channel side becomes the superheat degree target value (hereinafter, superheat degree control). Called). The degree of superheat of the refrigerant at the outlet of the liquid-gas heat exchanger 27 on the side of the supercooling refrigerant flow path is converted into a saturation temperature corresponding to the evaporation temperature by the suction pressure of the compressor 21 detected by the suction pressure sensor 33, and the bypass temperature. This is detected by subtracting the saturation temperature of the refrigerant from the refrigerant temperature detected by the sensor 63.

  When the compressor 21, the outdoor fan 26, and the indoor fan 43 are operated in the state of the refrigeration apparatus 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. Thereafter, the high-pressure gas refrigerant is sent to the outdoor heat exchanger 23 via the switching mechanism 22, exchanges heat with the outdoor air supplied by the outdoor fan 26, and is condensed to become a high-pressure liquid refrigerant. Then, after passing through the outdoor first expansion valve 25, the high-pressure liquid refrigerant flows into the liquid gas heat exchanger 27 and is further cooled by exchanging heat with the refrigerant flowing through the subcooling refrigerant flow path 61. It becomes supercooled. At this time, a part of the high-pressure liquid refrigerant condensed in the outdoor heat exchanger 23 is branched into the subcooling refrigerant flow path 61, and after being decompressed by the outdoor second expansion valve 62, the refrigerant enters the suction side of the compressor 21. Returned. Here, a part of the refrigerant passing through the outdoor second expansion valve 62 is evaporated by being depressurized to near the suction pressure of the compressor 21. Then, the refrigerant flowing from the outlet of the outdoor second expansion valve 62 of the supercooling refrigerant flow path 61 toward the suction side of the compressor 21 passes through the liquid gas heat exchanger 27 and the outdoor heat on the main refrigerant circuit side. Heat exchange is performed with the high-pressure liquid refrigerant sent from the exchanger 23 to the air conditioning indoor unit 4.

  The supercooled high-pressure liquid refrigerant is sent to the air conditioning indoor unit 4 via the liquid side closing valve 28 a and the first refrigerant communication pipe 6.

  The high-pressure liquid refrigerant sent to the air-conditioning indoor unit 4 is decompressed to near the suction pressure of the compressor 21 by the indoor expansion valve 41 to become a low-pressure gas-liquid two-phase refrigerant and sent to the indoor heat exchanger 42. In the indoor heat exchanger 42, heat is exchanged with the room air to evaporate to become a low-pressure gas refrigerant.

  This low-pressure gas refrigerant is sent to the air-conditioning outdoor unit 2 via the second refrigerant communication pipe 7, and is again sucked into the compressor 21 via the gas-side closing valve 28 b and the switching mechanism 22. As described above, the air conditioner 1 uses the outdoor heat exchanger 23 as a condenser for the refrigerant compressed in the compressor 21, and the indoor heat exchanger 42 is condensed in the outdoor heat exchanger 23 before the first refrigerant. The cooling operation is performed so as to function as an evaporator of the refrigerant sent through the communication pipe 6 and the indoor expansion valve 41.

(3-1-2) Cooling operation at the time of abnormality Switching from the cooling operation at the normal time to the cooling operation at the time of abnormality is that the indoor heat exchanger 42 is in an overcooled state in the indoor control device 47. It is when it is judged. When the indoor unit liquid pipe pressure saturation temperature Tein is higher than the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44 (Tein> Th2), the indoor controller 47 moves the indoor heat exchanger 42 in front of the indoor heat exchanger 42. Judged to be supercooled.

  The state where the indoor unit liquid pipe pressure saturation temperature Tein is higher than the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44 is a state where the indoor unit liquid pipe pressure saturation temperature Tein is operated in a refrigeration cycle as shown in FIG. is there. That is, in FIG. 3, the enthalpy hB of the refrigerant at the point B after being expanded by the indoor expansion valve 41 is lower than the enthalpy hA at the point A where the saturated liquid line L1 intersects the evaporation pressure P2. In such a state, since the refrigerant flowing into the indoor heat exchanger 42 has a supercooling degree, if the superheat degree control is performed based on the temperature difference between the front and back of the indoor heat exchanger 42, the actual superheat degree is erroneously detected. Resulting in. As a result, even though the refrigerant is in a two-phase state at the outlet of the indoor heat exchanger 42, it is mistakenly regarded as being overheated, and even if the opening degree of the indoor expansion valve 41 is slightly adjusted, the temperature of the refrigerant in the two-phase state is It may not change and become uncontrollable.

  Therefore, if the indoor control device 47 determines that Tein> Th2, the indoor superheat valve 41 is adjusted by switching the target value of the superheat degree of the refrigerant from the first superheat degree target value Tsh1 to the second superheat degree target value Tsh2. Do. Here, the second superheat degree target value Tsh2 is larger than the first superheat degree target value Tsh1 (Tsh2> Tsh1).

  The degree of supercooling at the inlet of the indoor heat exchanger 42 that can be generated is evaluated, and the superheat degree control is performed by changing to the second superheat degree target value Tsh2 set to a temperature higher than the first superheat degree target value Tsh1. As a result, the refrigerant at the outlet of the indoor heat exchanger 42 can be reliably used as a superheated refrigerant, thereby preventing deterioration of controllability.

  However, changing the superheat degree target value to the second superheat degree target value Tsh2 leads to a decrease in efficiency. Therefore, if it will be in the state which can be returned to 1st superheat degree target value Tsh1, the indoor control apparatus 47 will return the target value of superheat degree to 1st superheat degree target value Tsh1. Specifically, for example, the indoor control device 47 determines that the indoor unit liquid pipe pressure saturation temperature Tein is set to a temperature β (several degrees (eg, several degrees) that is set in advance from the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44. When it is detected that the temperature is lowered by 3 ° C.), the superheat degree target value is changed from the second superheat degree target value Tsh2 to the first superheat degree target value Tsh1. That is, the target value of the superheat degree is switched when the condition of Tein <Th2-β is satisfied. This temperature β is a margin for preventing hunting.

(3-2) Heating Operation During the heating operation, the switching mechanism 22 is in the state indicated by the broken line in FIG. 1, that is, the discharge side of the compressor 21 is heated in the room via the gas-side stop valve 28 b and the second refrigerant communication pipe 7. It is connected to the gas side of the exchanger 42 and the suction side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23. The opening degree of the outdoor first expansion valve 25 is adjusted in order to reduce the refrigerant flowing into the outdoor heat exchanger 23 to a pressure at which the refrigerant can be evaporated in the outdoor heat exchanger 23 (that is, evaporation pressure). ing. Moreover, the liquid side closing valve 28a and the gas side closing valve 28b are opened. The opening of the indoor expansion valve 41 is adjusted so that the degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is constant at the target value of the degree of supercooling. The degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is converted to a saturation temperature corresponding to the condensing temperature of the discharge pressure of the compressor 21 detected by the discharge pressure sensor 31, and from the saturation temperature of the refrigerant to the indoor liquid pipe. It is detected by subtracting the refrigerant temperature detected by the temperature sensor 44.

  When the compressor 21, the outdoor fan 26, and the indoor fan 43 are operated in the state of the refrigeration apparatus 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant, and the switching mechanism 22, gas The air is sent to the air conditioning indoor unit 4 via the side closing valve 28 b and the second refrigerant communication pipe 7.

  The high-pressure gas refrigerant sent to the air-conditioning indoor unit 4 exchanges heat with indoor air in the indoor heat exchanger 42 to condense into high-pressure liquid refrigerant, and then passes through the indoor expansion valve 41. At this time, the pressure is reduced according to the opening degree of the indoor expansion valve 41.

  The refrigerant that has passed through the indoor expansion valve 41 is sent to the air conditioning outdoor unit 2 via the first refrigerant communication pipe 6, and passes through the liquid side closing valve 28 a, the liquid gas heat exchanger 27, and the outdoor first expansion valve 25. After the pressure is further reduced, it flows into the outdoor heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with outdoor air supplied by the outdoor fan 26 to evaporate into a low-pressure gas refrigerant, and passes through the switching mechanism 22. Then, it is sucked into the compressor 21 again.

  The operation control as described above is performed by the air conditioning control device 8 (the indoor control device 47 and the outdoor control device 30 and the transmission line 8a connecting them) that performs the normal operation including the cooling operation and the heating operation.

(4) Features of the refrigeration apparatus (4-1) In the refrigeration apparatus 10 according to the present embodiment, during the cooling operation, the compressor 21, the outdoor heat exchanger 23 (radiator), the indoor heat exchanger 42 (evaporator), Are connected in order, and the indoor main refrigerant circuit 10a and the outdoor main refrigerant circuit 10c (refrigeration circuit) in which the refrigerant circulates are formed. The indoor expansion valve 41 (expansion mechanism) provided on the inflow side of the indoor heat exchanger 42 expands the refrigerant flowing into the indoor heat exchanger 42 based on the superheat degree target value on the outflow side of the indoor heat exchanger 42. To control. The indoor liquid pipe temperature sensor 44 and the suction pressure sensor 33 (detector) detect the supercooled state of the refrigerant on the inflow side of the indoor heat exchanger 42. When the indoor control device 47 (control unit) determines that the refrigerant on the inflow side of the indoor heat exchanger 42 is in a supercooled state based on the detection results of the indoor liquid pipe temperature sensor 44 and the suction pressure sensor 33, The setting change is made to raise the degree target value from the first superheat degree target value Tsh1 to the second superheat degree target value Tsh2.

  When it is determined that the refrigerant on the inflow side of the indoor heat exchanger 42 is in a supercooled state, the setting change is performed to increase the superheat degree target value, so that a situation in which the superheat degree control of the indoor heat exchanger 42 cannot be performed is avoided. Thus, the degree of superheat of the indoor heat exchanger 42 can be appropriately controlled. Therefore, the superheat degree control of the refrigeration apparatus 10 in which the refrigerant is likely to be in a supercooled state before the indoor heat exchanger 42 can be appropriately performed. In particular, since the amount of the refrigerant is large, it is possible to sufficiently cope with the case where the refrigerant is likely to be supercooled in front of the indoor heat exchanger 42 (use side heat exchanger) functioning as an evaporator.

  (4-2) The suction pressure sensor 33 is a first detector for detecting the pressure saturation temperature on the inflow side of the indoor heat exchanger 42 (use side heat exchanger), and the indoor liquid pipe temperature sensor 44 is It is a 2nd detector for detecting the temperature of the refrigerant | coolant of the inflow side of the indoor heat exchanger 42. FIG. The indoor control device 47 (control unit) determines whether the indoor unit liquid pipe pressure saturation temperature Tein is higher than the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44 (detection by the first detector and the second detector). Based on the comparison of the results, it is determined whether or not the refrigerant on the inflow side of the indoor heat exchanger 42 is in a supercooled state. Therefore, even if the refrigerant on the inflow side of the indoor heat exchanger 42 is supercooled, it is possible to accurately determine the supercooled state.

  Thus, the conventional indoor liquid pipe temperature sensor 44 is used as a second detector for determining whether or not the refrigerant on the inflow side of the indoor heat exchanger 42 (use side heat exchanger) is in a supercooled state. Therefore, an increase in cost can be suppressed. Similarly, the conventional suction pressure sensor 33 can be used as the first detector for determining whether or not the refrigerant on the inflow side of the indoor heat exchanger 42 is in a supercooled state. The rise can be suppressed.

(5) Modification (5-1) Modification A
In the refrigeration apparatus 10 of the above-described embodiment, the case where the indoor control device 47 increases the superheat degree target value when it is determined that the indoor heat exchanger 42 (evaporator) is in the supercooled state during the cooling operation will be described. However, the setting may be changed so that the outdoor control device 30 decreases the low-pressure target value when it is determined that the indoor control device 47 is in the supercooled state. In the case of the refrigeration apparatus 10, the low pressure target value is the indoor unit liquid pipe pressure saturation temperature Tein. In such a case, the air conditioning control device 8 becomes a control unit. The air-conditioning control device 8 changes the low-pressure target value from the first low-pressure target value PL1 to the second low-pressure target value PL2 lower than the first low-pressure target value PL1 based on the detection results of the indoor liquid pipe temperature sensor 44 and the suction pressure sensor 33 as described above. . That is, PL1> PL2.

  When the low pressure target value is changed to the second low pressure target value PL2 that is lower than the first low pressure target value PL1, the superheat degree target value does not change, so the pressure drop in the indoor expansion valve 41 increases and the evaporation pressure decreases. To do. As a result, the state of the refrigerant at the time B1 when it passes through the indoor expansion valve 41 is reduced to e.g. P3 as shown in FIG. 3, and the downstream side of the indoor expansion valve 41 (the inflow side of the indoor heat exchanger 42) ) Changes to a gas-liquid two-phase state, and control based on the degree of superheat becomes possible.

  When the second low pressure target value L2 is set, the indoor control device 47 operates, for example, assuming that the low pressure target upper limit is equal to the indoor unit liquid pipe pressure saturation temperature Tein target value equal to the indoor unit liquid pipe temperature Th2. When the operation is performed under such conditions and the low pressure (Tein) decreases due to a load factor or the like, the operation automatically shifts from the above-described determination condition to normal control. That is, the indoor control device 47 detects that the indoor unit liquid pipe pressure saturation temperature Tein is equal to or lower than the temperature Th2 detected by the indoor liquid pipe temperature sensor 44 (Tein ≦ Th2), and based on the detection result, the low pressure target. The value is changed from the second low pressure target value PL2 to the first low pressure target value PL1.

(5-2) Modification B
In the refrigeration apparatus 10 of the above embodiment, during cooling, when the indoor unit liquid pipe pressure saturation temperature Tein is higher than the refrigerant temperature Th2 detected by the indoor liquid pipe temperature sensor 44 (Tein> Th2), Although it is determined that the inflow side of the heat exchanger 42 is supercooled, it can also be determined using the outdoor unit liquid pipe inlet temperature T1. The outdoor unit liquid pipe inlet temperature T1 is a temperature detected by, for example, the liquid pipe temperature sensor 35 (third detector). The indoor control device 47 determines that the inflow side of the indoor heat exchanger 42 is supercooled when the condition of Tein> T1-α is satisfied in consideration of the heat loss. Then, the indoor control device 47 changes the superheat degree target value from the first superheat degree target value Tsh1 to the second superheat degree target value Tsh2 when this condition is satisfied, or changes the low pressure target value to the first low pressure target value PL1. To the second low pressure target value PL2. However, (alpha) is a value which concerns on heat loss, and is a value derived | led-out from experiment etc., for example, is about 3 degreeC.

  The switching of the superheat degree target value and the switching of the low pressure target value performed by the indoor control device 47 when it is determined that the inflow side of the indoor heat exchanger 42 is undercooling is the same as in the above-described embodiment and modification B. is there.

  In addition, whether the inflow side of the indoor heat exchanger 42 is changed from the supercooling state to the non-supercooling state to return the superheat degree target value or the low pressure target value to the original value is also determined by the outdoor unit liquid pipe inlet temperature. This is done using T1. That is, when it is detected that the condition of Tein ≦ T1-α−β is detected, the thermal temperature target value is changed from the second superheat degree target value Tsh2 to the first superheat degree target value Tsh1, or the low pressure target value is changed. The second low pressure target value PL2 is changed to the first low pressure target value PL1.

  Thus, the conventional liquid tube temperature sensor 35 (in the third detector for determining whether or not the refrigerant on the inflow side of the indoor heat exchanger 42 (use side heat exchanger) is in a supercooled state is used. Since a heat source side liquid pipe temperature sensor) can be used, an increase in cost can be suppressed. Similarly, the conventional suction pressure sensor 33 can be used as the first detector for determining whether or not the refrigerant on the inflow side of the indoor heat exchanger 42 is in a supercooled state. The rise can be suppressed.

(5-3) Modification C
In the above embodiment and the above modification A, the case where the indoor heat exchanger 42 functions as an evaporator during the cooling operation has been described. However, the refrigerant on the inflow side of the outdoor heat exchanger 23 is in a supercooled state during the heating operation. The present invention can also be applied to cases where it is likely to occur.

  Whether or not a supercooling state has occurred on the inflow side of the outdoor heat exchanger 23 is whether the condition of Tein> T1-α is satisfied using the low-pressure Tein and the outdoor unit liquid pipe inlet temperature T1 described above. It can be judged in the outdoor control device 30 by detecting whether or not.

  Since the high pressure target value is set during the heating operation, when it is determined that a supercooling state has occurred on the inflow side of the outdoor heat exchanger 23, the high pressure target value is changed from the first high pressure target value HP1 to the second high pressure target value. Change to the target value HP2. In this case, the second high pressure target value HP2 is set higher than the first high pressure target value HP1 (HP2> HP1).

  And if it detects that the conditions of Tein <= T1- (alpha)-(beta) are satisfy | filled similarly to the said embodiment and modification A, B, a high voltage | pressure target value will be returned to a normal state. That is, when it is determined that the supercooling state has been eliminated on the inflow side of the outdoor heat exchanger 23, the high pressure target value is changed from the second high pressure target value HP2 to the first high pressure target value HP1.

(5-4) Modification D
Although the said embodiment demonstrated the case where two same air-conditioning indoor units 4a and 4b were connected as a structure of the air-conditioning indoor unit 4, 1 unit | set or 3 or more air-conditioning indoor units may be connected. When a plurality of air conditioning indoor units are connected, air conditioning indoor units having different configurations may be connected.

(5-5) Modification E
In the above embodiment, the case where the superheat degree target value is changed to the second superheat degree target value Tsh2 set to a temperature higher than the first superheat degree target value Tsh1 has been described. However, a plurality of different superheat degree target values can be set as the second superheat degree target value. For example, when the third superheat degree target value Tsh3 higher than the second superheat degree target value Tsh2 is provided and the degree of supercooling Tsc satisfies the condition 0 <Tsc ≦ Tsc1, the second superheat degree target value Tsh2 is used to perform the supercooling. When the degree Tsc satisfies the condition of Tsc1 <Tsc, the third superheat degree target value Tsh3 may be used. In addition, a relational expression between the second superheat degree target value Tsh2 and the supercooling degree Tsc is prepared in advance, the supercooling degree at the inlet of the indoor heat exchanger 42 is evaluated, and the second superheating degree is calculated according to the degree of the supercooling degree. The superheat degree target value Tsh2 can be changed to a temperature higher than the first superheat degree target value Tsh1. Note that the relational expression between the second superheat degree target value Tsh2 and the supercooling degree Tsc may be determined as appropriate through, for example, an experiment or trial operation that is performed in advance.

DESCRIPTION OF SYMBOLS 10 Refrigeration apparatus 21 Compressor 23 Outdoor heat exchanger 30 Outdoor control apparatus 32 Discharge temperature sensor 33 Suction pressure sensor 41 Indoor expansion valve 42 Indoor heat exchanger 44 Indoor liquid pipe temperature sensor 47 Indoor control apparatus

Japanese Patent Laid-Open No. 2004-271066

Claims (7)

A compressor (21), a radiator (23, 42), and an evaporator (42, 23) are connected in order to form a refrigerant circuit (10) in which a refrigerant circuit for circulating refrigerant is formed,
The evaporator is provided on the inflow side of the evaporator, and is supplied to the evaporator based on at least one of a high pressure target value of the refrigerant circuit, a low pressure target value of the refrigerant circuit, and a superheat degree target value on the outflow side of the evaporator. An expansion mechanism (41) for controlling expansion of the refrigerant flowing in;
Detectors (29, 44, 35, 31) for detecting the supercooling state of the refrigerant on the inflow side of the evaporator;
When it is determined that the refrigerant on the inflow side of the evaporator is in a supercooled state based on the detection result of the detector, a setting change that increases the high pressure target value, a setting change that decreases the low pressure target value, and the degree of superheat A control unit (47, 30, 8) capable of performing at least one predetermined setting change among setting changes for increasing the target value;
A refrigeration apparatus comprising:   When the supercooling state is resolved after performing the predetermined setting change, the control unit restores the predetermined setting change.
The refrigeration apparatus according to claim 1.   The control unit determines a value when it is determined that the supercooling state is reached when the predetermined setting change is performed, and a value when it is determined that the supercooling state is canceled when the predetermined setting change is restored. A margin for preventing hunting is provided between
The refrigeration apparatus according to claim 2. The evaporator is a use side heat exchanger (42),
When the control unit (47) determines that the refrigerant on the inflow side of the use-side heat exchanger is in a supercooled state based on the detection result of the detector, the setting change to lower the low-pressure target value and the Can perform at least one of setting changes to increase the superheat target value,
The refrigeration apparatus according to any one of claims 1 to 3 . The detector includes a first detector (33) for detecting the pressure saturation temperature on the inflow side of the use side heat exchanger and a first detector for detecting the temperature of the refrigerant on the inflow side of the use side heat exchanger. 2 detector (44), or a first detector (33) and a third detector (35) for detecting the temperature of the refrigerant on the inflow side of the expansion mechanism,
The control unit is configured to inflow the user-side heat exchanger based on a comparison of detection results of the first detector and the second detector or a comparison of detection results of the first detector and the third detector. It can be determined whether the refrigerant on the side is in a supercooled state,
The refrigeration apparatus according to claim 4 . The third detector is a liquid pipe temperature sensor (35) provided on the outflow side of the radiator,
The controller is configured to subtract a correction value corresponding to a heat loss from the attachment position of the liquid pipe temperature sensor to the expansion mechanism from a temperature detected by the liquid pipe temperature sensor, and to obtain a refrigerant on the inflow side of the expansion mechanism. It can be determined whether or not the refrigerant on the inflow side of the use side heat exchanger is in a supercooled state using as the temperature of
The refrigeration apparatus according to claim 5 . The first detector is a suction pressure sensor (33) for detecting the pressure on the suction side of the compressor,
The control unit can calculate the pressure saturation temperature from the pressure detected by the suction pressure sensor,
The refrigeration apparatus according to claim 5 or 6 .

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