Air conditioning system

Abstract

To improve energy saving performance in an air conditioner.SOLUTION: An air conditioner includes a refrigerant circuit (50) having a compressor (51), a condenser (52), and an evaporator (54), performs a refrigeration cycle by circulating a refrigerant in the refrigerant circuit (50), and cools air in the evaporator (54). The air conditioner includes a detecting unit (64) for detecting the rotation speed of the compressor (51), a gas supply pipe (55) for sending the refrigerant discharged from the compressor (51) to the evaporator (54) while bypassing the condenser (52), a control valve (56) provided in the gas supply pipe (55), and a controller (70) for controlling the opening of the control valve (56) on the basis of the rotation speed of the compressor (51) detected by the detecting unit (64).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an air conditioner.

Background Art

[0002] Conventionally, an air conditioner having a refrigerant circuit has been known. In the refrigerant circuit of the air conditioner, a refrigeration cycle is performed by circulating the refrigerant.

[0003] The amount of refrigerant passing through the evaporator in the refrigerant circuit is controlled according to the heat exchange amount between the refrigerant and air. However, when the heat exchange amount (air conditioning load) is small, the refrigerant flow rate decreases, which may cause the refrigerating machine oil to run out and lead to a problem of the compressor burning out. Further, when the heat exchange amount is below the capacity control lower limit of the air conditioner, the air conditioner may stop and stable air conditioning may not be possible. As a countermeasure, there is a method of increasing the refrigerant flow rate by flowing hot gas through the evaporator (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventionally, the flow rate of the hot gas has been controlled based on the suction pressure of the compressor. In order to prevent the suction pressure of the compressor from decreasing, the hot gas is continuously flowed, so that the rotational speed of the compressor increases and it operates at the maximum output. As a result, the energy saving performance is lowered.

[0006] An object of the present disclosure is to enhance the energy saving performance in an air conditioner.

Means for Solving the Problems

[0007] A first aspect of this disclosure relates to an air conditioning system. The air conditioning system includes a refrigerant circuit (50) having a compressor (51), a condenser (52), and an evaporator (54), and circulates a refrigerant in the refrigerant circuit (50) to perform a refrigeration cycle, and cools the air in the evaporator (54). The air conditioning system includes a detection unit (64) for detecting the rotational speed of the compressor (51), a gas supply pipe (55) for sending the refrigerant discharged from the compressor (51) to the evaporator (54) by bypassing the condenser (52), a control valve (56) provided in the gas supply pipe (55), and a controller (70) for controlling the opening degree of the control valve (56) based on the rotational speed of the compressor (51) detected by the detection unit (64).

[0008] According to the first embodiment, by controlling the opening of the control valve (56) so that the rotational speed of the compressor (51) reaches a predetermined target rotational speed (for example, the minimum rotational speed at which problems such as seizure of the compressor (51) or shutdown of the compressor (51) due to a decrease in heat exchange rate do not occur), the compressor (51) can be operated stably without being operated at maximum output, thereby improving energy efficiency.

[0009] A second aspect of the present disclosure is that, in the first aspect described above, the controller (70) controls the opening degree of the control valve (56) so that the rotational speed of the compressor (51) detected by the detection unit (64) becomes a predetermined target rotational speed.

[0010] In the second embodiment, the rotational speed of the compressor (51) can be brought closer to a predetermined target rotational speed.

[0011] A third aspect of the present disclosure is, in the second aspect described above, the controller (70) increases the opening of the control valve (56) when the rotational speed of the compressor (51) is lower than the predetermined target rotational speed, and decreases the opening of the control valve (56) when the rotational speed of the compressor (51) is higher than the predetermined target rotational speed.

[0012] In the third embodiment, the rotational speed of the compressor (51) can be effectively brought closer to a predetermined target rotational speed.

[0013] A fourth aspect of this disclosure is that, in any one of the first to third aspects described above, the detection unit (64) is a frequency sensor that detects the drive frequency of the compressor (51).

[0014] In the fourth embodiment, the rotational speed of the compressor (51) can be detected by a frequency sensor. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a schematic diagram of the user-side unit of the air conditioning system. [Figure 2] Figure 2 is a piping diagram showing the refrigerant circuit of an air conditioning system. [Modes for carrying out the invention]

[0016] The embodiments of this disclosure will be described in detail below with reference to the drawings. This disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual explanation of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding. In each embodiment, modification, and drawing, the same or corresponding parts are denoted by the same reference numerals, and detailed descriptions and their associated effects will not be repeated.

[0017] The embodiments will now be described. The air conditioning system (10) of this embodiment provides air conditioning for a test chamber (100) used for driving tests of automobiles, etc.

[0018] The air conditioning system (10) comprises a user-side unit (20) and a heat source-side unit (40). The air conditioning system also includes a refrigerant circuit (50).

[0019] -User-side unit- As shown in FIG. 1, the user-side unit (20) is a so-called air handling unit. The user-side unit (20) includes a casing (25). An intake port (27) is formed on one end face of the casing (25), and an outlet port (28) is formed on the other end face of the casing (25). An air flow path (26) is formed inside the casing (25) from the intake port (27) to the outlet port (28).

[0020] The user-side unit (20) is connected to the laboratory (100) via an intake duct (16) and an outlet duct (17). The intake duct (16) is connected to the intake port (27) of the casing (25) and communicates the air flow path (26) with the internal space of the laboratory (100). The outlet duct (17) is connected to the outlet port (28) of the casing (25) and communicates the air flow path (26) with the internal space of the laboratory (100).

[0021] In the air flow path (26) inside the casing (25), a filter (31), an evaporator (54), an electric heater (32), and a user-side fan (33) are provided in order from the intake port (27) side to the outlet port (28) side. The filter (31) collects dust and the like contained in the air flowing in from the intake port (27). The evaporator (54) is connected to a refrigerant circuit (50) and cools the air. The electric heater (32) heats the air that has passed through the evaporator (54). The user-side fan (33) sucks in the air that has passed through the electric heater (32) and blows the air toward the outlet port (28).

[0022] <Operation and Movement> The operation and movement of the user-side unit (20) will be described.

[0023] When the user-side fan (33) operates, the air in the internal space of the laboratory (100) flows into the air flow path (26) inside the casing (25) through the intake duct (16). The air flowing through the air flow path (26) passes through the filter (31), the evaporator (54), and the electric heater (32) in order.

[0024] The air is cooled as it passes through the evaporator (54) and heated as it passes through the electric heater (32). The electric heater (32) may temporarily stop heating the air. The air that has passed through the electric heater (32) is blown out from the user-side fan (33) into the discharge duct (17) and then blown out into the interior space of the test chamber (100).

[0025] -Air temperature sensor, heater controller- The air conditioning system (10) includes an air temperature sensor (36) and a heater controller (37).

[0026] The air temperature sensor (36) is installed in the discharge duct (17) and measures the temperature of the air flowing through the discharge duct (17). The value measured by the air temperature sensor (36) indicates the temperature of the air supplied by the user-side unit (20) to the internal space of the test chamber (100).

[0027] The heater controller (37) receives the measurement value from the air temperature sensor (36). Based on the measurement value from the air temperature sensor (36), the heater controller (37) controls the heating amount of the electric heater (32). Specifically, the heater controller (37) adjusts the heating amount of the electric heater (32) so that the measurement value from the air temperature sensor (36) is equal to the set air temperature. If the measurement value from the air temperature sensor (36) is lower than the set air temperature, the heater controller (37) increases the heating amount of the electric heater (32). If the measurement value from the air temperature sensor (36) is higher than the set air temperature, the heater controller (37) decreases the heating amount of the electric heater (32).

[0028] - Refrigerant Circuit - The refrigerant circuit (50) is a closed circuit filled with refrigerant. The refrigerant circuit (50) performs a refrigeration cycle by circulating the refrigerant.

[0029] As shown in Figure 2, the refrigerant circuit (50) comprises a compressor (51), a condenser (52), an expansion valve (53), and an evaporator (54). In the refrigerant circuit (50), the condenser (52), expansion valve (53), and evaporator (54) are arranged in order from the discharge port to the inlet port of the compressor (51). Between the condenser (52) and the expansion valve (53) in the refrigerant circuit (50), a receiver (57) is provided to store excess refrigerant due to fluctuations in the heat load.

[0030] The compressor (51) compresses and discharges the inhaled refrigerant. Although not shown in the diagram, the compressor (51) comprises a compression mechanism and an electric motor that drives the compression mechanism. The condenser (52) is a cross-fin type air heat exchanger that exchanges heat between the refrigerant and the outside air. The expansion valve (53) is an electrically operated expansion valve with a variable opening. The evaporator (54) is a cross-fin type air heat exchanger that exchanges heat between the refrigerant and the air in the air passage (26).

[0031] The refrigerant circuit (50) also includes a gas supply pipe (55). The gas supply pipe (55) constitutes a gas supply passage. The gas supply pipe (55) sends the refrigerant discharged from the compressor (51) to the evaporator (54), bypassing the condenser (52). One end of the gas supply pipe (55) is connected to the piping between the discharge port of the compressor (51) and the condenser (52). The other end of the gas supply pipe (55) is connected to the piping between the expansion valve (53) and the evaporator (54). A control valve (56) is provided in the gas supply pipe (55). The control valve (56) is an electrically operated valve with a variable opening.

[0032] <Refrigeration cycle> The refrigeration cycle performed by the refrigerant circuit (50) will be described below.

[0033] When the compressor (51) is operating, the refrigerant circulates in the refrigerant circuit (50). The refrigerant discharged by the compressor (51) flows into the condenser (52), where it condenses by releasing heat into the outdoor air passing through the condenser (52). The refrigerant flowing out of the condenser (52) is depressurized as it passes through the expansion valve (53), and then flows into the evaporator (54).

[0034] When the control valve (56) is open, a portion of the gaseous refrigerant (hot gas) discharged from the compressor (51) flows into the gas supply pipe (55). The gaseous refrigerant flowing through the gas supply pipe (55), along with the refrigerant that has passed through the expansion valve (53), flows into the evaporator (54). The refrigerant that flows into the evaporator (54) absorbs heat from the air passing through the evaporator (54) and evaporates. The refrigerant that flows out of the evaporator (54) is drawn into the compressor (51) and compressed. The compressor (51) compresses the drawn-in refrigerant and discharges it.

[0035] -Heat source unit- The heat source unit (40) is equipped with a compressor (51) and a condenser (52) of the refrigerant circuit (50). The heat source unit (40) also includes a heat source fan (41) and an inverter (42). The heat source fan (41) supplies outdoor air to the condenser (52). Although not shown in the diagram, an external power source such as a commercial power supply is connected to the inverter (42). The inverter (42) converts the frequency of the supplied AC to a set frequency and supplies the AC of the set frequency to the motor of the compressor (51). Changing the output frequency of the inverter (42) changes the rotational speed of the compressor (51).

[0036] The heat source unit (40) is equipped with an intake pressure sensor (46). The intake pressure sensor (46) is connected to the refrigerant circuit (50). The intake pressure sensor (46) is attached to a pipe connected to the intake port of the compressor (51) and measures (detects) the pressure of the refrigerant being drawn into the compressor (51).

[0037] <Compressor controller> The heat source unit (40) includes a compressor controller (47). The compressor controller (47) receives the measured value (detection result) from the intake pressure sensor (46). The compressor controller (47) is configured to control the rotational speed of the compressor (51) based on the measured value from the intake pressure sensor (46).

[0038] Specifically, the compressor controller (47) adjusts the rotational speed of the compressor (51) so that the value measured by the intake pressure sensor (46) becomes the set intake pressure. If the value measured by the intake pressure sensor (46) is lower than the set intake pressure, the compressor controller (47) lowers the rotational speed of the compressor (51) by lowering the output frequency of the inverter (42). If the value measured by the intake pressure sensor (46) is higher than the set intake pressure, the compressor controller (47) raises the rotational speed of the compressor (51) by raising the output frequency of the inverter (42).

[0039] -Sensor- The air conditioning unit (10) includes an outlet pressure sensor (62), an outlet temperature sensor (63), and a frequency sensor (64).

[0040] The outlet pressure sensor (62) and the outlet temperature sensor (63) are attached to the piping connected to the outlet of the evaporator (54). The outlet pressure sensor (62) detects the pressure of the refrigerant flowing out of the evaporator (54) and the pressure of the refrigerant flowing from the evaporator (54) towards the compressor (51). The outlet pressure sensor (62) is an example of a third detection unit. The outlet temperature sensor (63) detects the temperature of the refrigerant flowing out of the evaporator (54) and the temperature of the refrigerant flowing from the evaporator (54) towards the compressor (51). The outlet pressure sensor (62) is an example of a second detection unit.

[0041] The frequency sensor (64) is installed in the electrical wiring that supplies power to the motor of the compressor (51) from the inverter (42). The frequency sensor (64) measures the output frequency of the inverter (42). The value measured by the frequency sensor (64) is the frequency of the AC power supplied by the inverter (42) to the compressor (51), or in other words, the driving frequency of the compressor (51).

[0042] -Controller- The air conditioning system (10) includes an expansion valve controller (75) and a control valve controller (76). The compressor controller (47), the expansion valve controller (75), and the control valve controller (76) constitute a controller (70) that controls the expansion valve (53) and the control valve (56).

[0043] <Expansion valve controller> The expansion valve controller (75) receives the measured value from the outlet pressure sensor (62) and the measured value from the outlet temperature sensor (63). The expansion valve controller (75) is configured to calculate a first command value for the opening degree of the expansion valve (53) based on the measured values ​​from the outlet pressure sensor (62) and the outlet temperature sensor (63).

[0044] First, the expansion valve controller (75) calculates the degree of superheating of the refrigerant at the outlet of the evaporator (54). The expansion valve controller (75) subtracts the refrigerant saturation temperature Ts corresponding to the measurement value of the outlet pressure sensor (62) from the measurement value T of the outlet temperature sensor (63), and defines the value obtained as the degree of superheating of the refrigerant at the outlet of the expansion valve (53) SH (=T-Ts).

[0045] Next, the expansion valve controller (75) calculates the opening degree of the expansion valve (53) such that the superheating degree of the refrigerant at the outlet of the evaporator (54) becomes the set superheating degree. This opening degree calculated by the expansion valve controller (75) is the first opening degree. The expansion valve controller (75) determines the calculated first opening degree as the first command value for the opening degree of the expansion valve (53). The control valve controller (76) transmits the determined first command value to the expansion valve (53). As a result, the opening degree of the expansion valve (53) becomes the first opening degree corresponding to the first command value.

[0046] If the refrigerant at the outlet of the evaporator (54) becomes wet, the liquid refrigerant may be drawn into the compressor (51), potentially damaging it. Therefore, to prevent damage to the compressor (51), it is necessary to maintain the refrigerant at the outlet of the evaporator (54) in a single-phase gaseous state.

[0047] On the other hand, changing the opening of the expansion valve (53) changes the amount of refrigerant flowing into the evaporator (54), and as a result, the state of the refrigerant at the outlet of the evaporator (54) changes. Therefore, the expansion valve controller (75) calculates the opening of the expansion valve (53) such that the superheating degree of the refrigerant at the outlet of the evaporator (54) becomes a set superheating degree (for example, a value within the range of 5K or more and 10K or less), thereby completely gasifying the refrigerant at the outlet of the evaporator (54).

[0048] When the opening of the expansion valve (53) decreases, the amount of refrigerant flowing into the evaporator (54) decreases, and as a result, the degree of superheating of the refrigerant at the outlet of the evaporator (54) increases. Therefore, if the degree of superheating of the refrigerant at the outlet of the evaporator (54) is lower than the set degree of superheating, the expansion valve controller (75) determines a smaller opening of the expansion valve (53) than the current opening as the first command value.

[0049] On the other hand, when the opening of the expansion valve (53) is increased, the amount of refrigerant flowing into the evaporator (54) increases, and as a result, the degree of superheating of the refrigerant at the outlet of the evaporator (54) decreases. Therefore, if the degree of superheating of the refrigerant at the outlet of the evaporator (54) is higher than the set degree of superheating, the expansion valve controller (75) determines a first command value that is larger than the current opening of the expansion valve (53).

[0050] <Control valve controller> The control valve controller (76) receives the measurement value from the frequency sensor (64). The control valve controller (76) is configured to calculate a second command value related to the opening degree of the control valve (56) based on the measurement value from the frequency sensor (64). In other words, the measurement value from the frequency sensor (64) is the rotational speed of the compressor (51).

[0051] Specifically, the control valve controller (76) calculates the opening degree of the control valve (56) such that the measurement value of the frequency sensor (64) becomes the set frequency. This opening degree calculated by the control valve controller (76) is the second opening degree. The control valve controller (76) determines the calculated second opening degree as the second command value for the opening degree of the control valve (56). The control valve controller (76) transmits the determined second command value to the control valve (56). As a result, the opening degree of the control valve (56) becomes the second opening degree corresponding to the second command value.

[0052] Here, when the compressor (51) is rotating at a low speed, the flow velocity of the refrigerant flowing through the refrigerant circuit (50) is low, and the refrigerant oil discharged from the compressor (51) along with the refrigerant tends to accumulate in the evaporator (54) and piping. Therefore, when the compressor (51) is operating at a relatively low rotational speed (for example, 20% or less of the maximum rotational speed) for a long period of time, the amount of refrigerant oil accumulating outside the compressor (51) increases, and the amount of refrigerant oil remaining inside the compressor (51) decreases. As a result, the amount of refrigerant oil supplied to the sliding parts of the compressor (51) becomes insufficient, and the compressor (51) may be damaged.

[0053] On the other hand, if the rotational speed of the compressor (51) is kept at a relatively high rotational speed (for example, 80% or more of the maximum rotational speed), a sufficient amount of refrigerant oil will be returned to the compressor (51) along with the refrigerant. As a result, a sufficient amount of refrigerant oil will be stored in the compressor (51), and damage to the compressor (51) will be prevented.

[0054] Therefore, the control valve controller (76) calculates the opening degree of the control valve (56) such that the value measured by the frequency sensor (64) becomes the set frequency. The set frequency is, for example, a frequency of about 60% of the maximum output frequency specified in the specifications. The value measured by the frequency sensor (64) is the actual value of the output frequency of the inverter (42). As a result, when the value measured by the frequency sensor (64) becomes the set frequency, the rotational speed of the compressor (51) becomes the predetermined target rotational speed, and as a result, the amount of refrigerant oil that returns to the compressor (51) along with the refrigerant is secured.

[0055] Here, when the cooling load of the evaporator (54) (specifically, the amount of heat absorbed by the refrigerant from the air in the evaporator (54)) decreases, the amount of refrigerant evaporating in the evaporator (54) decreases, causing the measurement value of the suction pressure sensor (46) to drop. Therefore, if no action is taken, the compressor controller (47) will reduce the rotational speed of the compressor (51) in order to maintain the measurement value of the suction pressure sensor (46) at the set suction pressure. In such cases, the decrease in the rotational speed of the compressor (51) can be suppressed by increasing the flow rate of the gaseous refrigerant flowing through the gas supply pipe (55).

[0056] Let me explain the reason. The evaporator (54) receives a mixture of refrigerant that has passed through the expansion valve (53) and gaseous refrigerant flowing through the gas supply pipe (55). A portion of the liquid refrigerant contained in the refrigerant that has passed through the expansion valve (53) is heated by the gaseous refrigerant flowing in from the gas supply pipe (55) and evaporates. Therefore, when the opening of the control valve (56) is increased and the flow rate of gaseous refrigerant flowing through the gas supply pipe (55) increases, the amount of gaseous refrigerant that the compressor (51) draws in from the evaporator (54) increases. As a result, the decrease in the measured value of the suction pressure sensor (46) is suppressed, and the decrease in the rotational speed of the compressor (51) is also suppressed.

[0057] Therefore, if the measurement value of the frequency sensor (64) is lower than the set frequency, the control valve controller (76) determines a second command value that is larger than the current opening of the control valve (56). In other words, if the rotational speed of the compressor (51) is lower than a predetermined target rotational speed, the control valve controller (76) increases the opening of the control valve (56) compared to the current opening. The predetermined target rotational speed is, for example, about 60% of the maximum rotational speed specified in the specifications.

[0058] On the other hand, if the measurement value of the frequency sensor (64) is higher than the set frequency, it may be possible to maintain the rotational speed of the compressor (51) at or above a predetermined target rotational speed even if the opening of the control valve (56) is reduced. Therefore, if the measurement value of the frequency sensor (64) is higher than the set frequency, the control valve controller (76) determines a second command value that is smaller than the current opening of the control valve (56). In other words, if the rotational speed of the compressor (51) is higher than the predetermined target rotational speed, the control valve controller (76) reduces the opening of the control valve (56) to a smaller value than the current opening.

[0059] The control valve controller (76) determines a second command value such that the measurement value of the frequency sensor (64) becomes the set frequency. In other words, the control valve controller (76) controls the opening of the control valve (56) so that the rotational speed of the compressor (51) becomes the predetermined target rotational speed. As a result, energy efficiency can be improved while ensuring that the amount of refrigerant oil that returns to the compressor (51) along with the refrigerant is secured.

[0060] Incidentally, if the opening degree of the control valve (56) changes significantly in a short period of time, the pressure of the refrigerant flowing into the evaporator (54) will change, and the expansion valve controller (75) may change the opening degree of the expansion valve (53) in response. Therefore, the control valve controller (76) determines a second command value such that the change in the opening degree of the control valve (56) is a gradual change such that the measured value of the inlet pressure sensor (61) is kept substantially constant.

[0061] As described above, the control valve controller (76) controls the opening of the control valve (56) so that the rotational speed of the compressor (51) reaches the predetermined target rotational speed. By setting the predetermined target rotational speed to the minimum rotational speed that does not cause problems such as the compressor (51) seizing up or the compressor (51) stopping due to a decrease in the heat exchange rate of the evaporator (54), the compressor (51) can be operated stably without being operated at maximum output, thereby improving energy efficiency.

[0062] Other embodiments The following modifications may be applied to the air conditioning system (10) of the above embodiment. These modifications may be combined or substituted as appropriate, as long as they do not impair the function of the air conditioning system (10).

[0063] The air conditioning system (10) of this embodiment is not limited to providing air conditioning to a test room (100). The air conditioning system (10) of this embodiment may be used, for example, to provide air conditioning to a large space such as a hall.

[0064] Furthermore, in the air conditioning system (10) of this embodiment, the expansion valve controller (75) and the control valve controller (76) may each include a microcomputer. Also, the controller (70) may be composed of a single microcomputer. In addition, the microcomputer constituting the controller (70) may be configured to also perform the control operations performed by at least one of the controllers, the compressor controller (47) and the heater controller (37).

[0065] Furthermore, in the air conditioning system (10) of this embodiment, the measurement value of the frequency sensor (64) is configured to indicate the rotational speed of the compressor (51), but the present invention is not limited thereto. The command value to the inverter (42) for driving the motor of the compressor (51) may be configured to indicate the rotational speed of the compressor (51). In other words, the detection unit may be configured to acquire the command value to the inverter (42).

[0066] While embodiments and modifications have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, elements of the embodiments, modifications, and other embodiments described above may be combined or substituted as appropriate. In addition, the designations "first," "second," "third," etc. in the specification and claims are used to distinguish the phrases to which these designations are given, and do not limit the number or order of such phrases. [Industrial applicability]

[0067] As explained above, this disclosure is useful for air conditioning systems. [Explanation of Symbols]

[0068] 10. Air conditioning system 50 Refrigerant Circuit 51 Compressor 52 Condenser 53 Expansion valve 54 Evaporator 55 Gas supply pipe 56 Control valve 64 Frequency Sensor (Detection Unit) 70 Controllers

Claims

1. An air conditioning system comprising a refrigerant circuit (50) having a compressor (51), a condenser (52), and an evaporator (54), wherein a refrigerant is circulated in the refrigerant circuit (50) to perform a refrigeration cycle, and the air is cooled in the evaporator (54), A detection unit (64) for detecting the rotational speed of the compressor (51), A gas supply pipe (55) for sending the refrigerant discharged from the compressor (51) to the evaporator (54) by bypassing the condenser (52), A control valve (56) is provided in the gas supply pipe (55), A controller (70) controls the opening degree of the control valve (56) based on the rotational speed of the compressor (51) detected by the detection unit (64). Equipped with, The controller (70) is If the rotational speed of the compressor (51) is lower than a predetermined target rotational speed, the opening of the control valve (56) is increased. If the rotational speed of the compressor (51) is higher than the predetermined target rotational speed, the opening of the control valve (56) is reduced. An air conditioning system that controls the opening degree of the control valve (56) so that the rotational speed of the compressor (51) detected by the detection unit (64) becomes the predetermined target rotational speed.

2. The air conditioning device according to claim 1, wherein the detection unit (64) is a frequency sensor for detecting the drive frequency of the compressor (51).

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