Refrigeration cycle device and air conditioning device

Abstract

Provided is a refrigeration cycle device that has a refrigerant circuit which is configured by connecting a compressor, a condenser, an expansion valve, and an evaporator by piping and which circulates a refrigerant mixture having a temperature gradient, said refrigeration cycle device comprising: a two-phase pipe temperature sensor that detects the temperature at which the refrigerant mixture passing through the inside of the evaporator passes through a heat exchanger; and a control device that corrects the temperature at which said refrigerant mixture passes through the heat exchanger as detected by the two-phase pipe temperature sensor, that determines, on the basis of the corrected temperature, whether or not to perform condensation control, and that performs condensation control on the basis of the determination.

Description

[Technical Field]

[0001] This technology relates to a refrigeration cycle device and an air conditioner. In particular, it is related to the prevention of condensation in a refrigerant circuit using a refrigerant with a temperature gradient. restraint It's about control. [Background technology]

[0002] Refrigeration cycle devices such as air conditioners operate by circulating a refrigerant filled in a refrigerant circuit and exchanging heat with a fluid such as air or water to heat or cool the fluid. Here, the global warming potential (GWP) of the refrigerant used in refrigeration cycle devices is sometimes taken into consideration. Refrigerants with a high GWP can cause global warming and other problems if released into the atmosphere. For this reason, due to increased environmental awareness, there is a trend toward refrigerants with lower GWP values ​​for refrigeration cycle devices. Therefore, in recent years, non-azeotropic refrigerant mixtures, which are mixtures of multiple refrigerants with different boiling points, have been used as refrigerants with a low GWP.

[0003] In addition, a control device that controls the equipment of a refrigeration cycle device corrects the evaporation temperature by performing calculations from physical quantities such as temperature detected by a detection device such as a sensor (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-185116 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, in the refrigeration cycle device, a dew condensation control is performed based on the evaporation temperature, etc., to prevent condensation from occurring in the refrigerant circuit. restraintHowever, in the case of a refrigerant circuit using a refrigerant with a temperature gradient, such as a non-azeotropic refrigerant mixture, the temperature of the refrigerant varies during the evaporation process, so there is a possibility that the correct correction will not be performed. restraint There was a possibility that some parts would become colder than the temperature used for control judgment, causing condensation.

[0006] Therefore, even when a refrigerant with a temperature gradient is used, restraint The object is to provide a refrigeration cycle device and an air conditioner that can perform control more accurately. [Means for solving the problem]

[0007] The refrigeration cycle device according to the present disclosure is configured by connecting a compressor, a condenser, an expansion valve, and an evaporator through pipes, and has a refrigerant circuit for circulating a mixed refrigerant having a temperature gradient. The refrigeration cycle device includes a two-phase pipe temperature sensor for detecting the heat exchanger passing temperature of the mixed refrigerant passing through the evaporator, and a two-phase pipe temperature sensor for correcting the heat exchanger passing temperature detected by the two-phase pipe temperature sensor and calculating the condensation temperature based on the corrected temperature. inhibitory control It determines whether to perform dew removal, and restraint and a control device for controlling the The control device has a drive frequency acquisition unit that acquires the drive frequency of the compressor, a circulation amount estimation unit that estimates the refrigerant circulation amount of the mixed refrigerant based on the drive frequency, a correction determination unit that determines a correction value for the heat exchanger passage temperature detected by the two-phase pipe temperature sensor based on the estimated refrigerant circulation amount and a predetermined threshold value, and a correction unit that corrects the heat exchanger passage temperature based on the determination by the correction determination unit. This is what is done.

[0008] The air conditioner according to the present disclosure cools and heats a target space using the above-described refrigeration cycle device. [Effects of the Invention]

[0009] According to the disclosed refrigeration cycle device and air conditioner, the control device corrects the heat exchanger passing temperature detected by the two-phase pipe temperature sensor, and determines whether condensation occurs based on the corrected temperature. restraint Determine whether to control the dew restraint Therefore, the temperature passing through the heat exchanger is corrected to a more accurate temperature, and the condensation is reduced. restraint Therefore, the refrigeration cycle device can determine whether to control the amount of dew based on a more accurate dryness state. restraint Control can be exercised. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a configuration of a refrigeration cycle device according to a first embodiment. [Figure 2] 1 is a diagram showing a schematic configuration of an example of a heat exchanger according to a first embodiment. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a control device 400 in an air conditioning apparatus 1 according to Embodiment 1. [Figure 4] This is a pH diagram for a refrigeration cycle device. [Figure 5] 4 is a diagram showing the relationship between pressure and temperature in the evaporation process of a non-azeotropic refrigerant mixture when the pressure inside the evaporator is constant in the refrigeration cycle device according to the first embodiment. FIG. [Figure 6] 4 is a diagram showing the relationship between pressure and temperature in the evaporation process of a non-azeotropic refrigerant mixture when a pressure difference occurs inside the evaporator in the refrigeration cycle device according to the first embodiment. FIG. [Figure 7] 4 is a diagram showing the change over time in refrigerant temperature when the amount of refrigerant circulating is small in the indoor heat exchanger 110 of the air conditioner 1 according to Embodiment 1. FIG. [Figure 8] FIG. 3 is a diagram showing the change over time in refrigerant temperature when the amount of refrigerant circulating is large in the indoor heat exchanger 110 of the air conditioner 1 according to Embodiment 1. [Figure 9] FIG. 10 is a diagram illustrating the process of condensation suppression control of the refrigeration cycle device according to the second embodiment. [Figure 10] FIG. 10 is a diagram showing a configuration of a control device 400 according to a third embodiment. [Figure 11] FIG. 10 is a diagram showing a configuration of a control device 400 according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Refrigeration cycle devices and the like according to embodiments will be described below with reference to the drawings. In the following drawings, components with the same reference numerals are identical or equivalent and will be common throughout the following embodiments. The dimensional relationships between components in the drawings may differ from those in reality. The configurations of components shown throughout the specification are merely illustrative and are not limited to those described in the specification. In particular, the combinations of components are not limited to those in each embodiment; components described in other embodiments may be applied to other embodiments. Furthermore, the levels of pressure and temperature are not determined in relation to absolute values, but are determined relatively in terms of the state and operation of the device. When multiple similar devices are distinguished by subscripts, the subscripts may be omitted if there is no need to distinguish or identify them.

[0012] Embodiment 1 FIG. 1 is a diagram showing the configuration of a refrigeration cycle apparatus according to a first embodiment. Here, as an example of a refrigeration cycle apparatus, an air conditioner 1 that conditions the air of a room, which is a space to be air-conditioned, will be described. As shown in FIG. 1, the air conditioner 1 of the first embodiment has an outdoor unit 200, an indoor unit 100, and two refrigerant pipes 300. A compressor 210, a four-way valve 220, an outdoor heat exchanger 230, and an expansion valve 240 of the outdoor unit 200 are connected to an indoor heat exchanger 110 of the indoor unit 100 via the refrigerant pipes 300, forming a refrigerant circuit that circulates refrigerant to supply heat. The indoor unit 100 may also have the expansion valve 240. The air conditioner 1 of the first embodiment is configured such that one outdoor unit 200 and one indoor unit 100 are connected via pipes. However, the number of units that can be connected is not limited to this.

[0013] The air conditioner 1 uses a non-azeotropic refrigerant mixture as the refrigerant circulating within the refrigerant circuit. A non-azeotropic refrigerant mixture is a refrigerant mixture of multiple refrigerant components whose composition changes when evaporating and condensing. A non-azeotropic refrigerant mixture is in a two-phase gas-liquid state under the same pressure and does not maintain a constant temperature as its composition changes. For example, during the evaporation process under the same pressure, the refrigerant temperature at the end of evaporation is higher than the refrigerant temperature at the start of evaporation. Similarly, during the condensation process under the same pressure, the refrigerant temperature at the end of condensation is lower than the refrigerant temperature at the start of condensation. The temperature difference between the start and end of evaporation or condensation is the temperature gradient. Here, the non-azeotropic refrigerant mixture used in the air conditioner 1 in the first embodiment is R454B refrigerant, which is a mixture of HFC (hydrofluorocarbon) refrigerants R32 and R1234yf refrigerants in a ratio of 68.1:31.9.

[0014] The outdoor unit 200 in the first embodiment has, as devices that configure a refrigerant circuit, a compressor 210, a four-way valve 220, and an outdoor heat exchanger 230. The outdoor unit 200 also has an outdoor blower 250 and a control device 400.

[0015] The compressor 210 compresses the drawn refrigerant and discharges it. The compressor 210 is, for example, a scroll compressor, a rotary compressor, or a vane compressor. Here, the compressor 210 can change the circulation amount of the refrigerant discharged from the compressor 210 by arbitrarily changing the drive frequency using, for example, an inverter circuit.

[0016] The four-way valve 220 serving as the flow path switching device is a valve that switches the flow of refrigerant between, for example, cooling operation and heating operation. During heating operation, the four-way valve 220 connects the discharge side of the compressor 210 to the indoor heat exchanger 110 and also connects the suction side of the compressor 210 to the outdoor heat exchanger 230. During cooling operation, the four-way valve 220 connects the discharge side of the compressor 210 to the outdoor heat exchanger 230 and also connects the suction side of the compressor 210 to the indoor heat exchanger 110. While the four-way valve 220 is used here as an example, the flow path switching device is not limited to this. For example, a combination of multiple two-way valves may also be used as the flow path switching device.

[0017] The outdoor heat exchanger 230 is a heat exchanger that exchanges heat between the refrigerant and outdoor air. The outdoor heat exchanger 230 in the first embodiment functions as an evaporator during heating operation, absorbing heat to evaporate the refrigerant, and vaporizing it into a gaseous refrigerant (hereinafter referred to as a gas refrigerant) to be passed. On the other hand, the outdoor heat exchanger 230 functions as a condenser during cooling operation, condensing the refrigerant to release heat, and liquefying it into a liquid refrigerant (hereinafter referred to as a liquid refrigerant) to be passed. Furthermore, when driven, the outdoor blower 250 forms a flow of air that passes air from outside the outdoor unit 200 through the outdoor heat exchanger 230 and flows out of the outdoor unit 200, thereby promoting heat exchange in the outdoor heat exchanger 230.

[0018] Expansion valve 240, which functions as a throttle device or the like, is a valve that reduces the pressure of the refrigerant to expand it. Expansion valve 240 is, for example, an electronic expansion valve. Expansion valve 240 adjusts its opening based on instructions from control device 400 (described later) or the like, reduces the pressure, and controls the amount of refrigerant passing through.

[0019] The indoor unit 100 conditions the air inside the room. The indoor unit 100 has an indoor heat exchanger 110 as a component of a refrigerant circuit. The indoor unit 100 also has an indoor fan 120. The indoor heat exchanger 110 is a heat exchanger that exchanges heat between the air in the room, which is the space to be air-conditioned, and the refrigerant. For example, during heating operation, the indoor heat exchanger 110 functions as a condenser, condensing the refrigerant and passing the liquid refrigerant. During cooling operation, the indoor heat exchanger 110 functions as an evaporator, evaporating the refrigerant and passing the gas refrigerant. The indoor fan 120 passes air through the indoor heat exchanger 110 to promote heat exchange in the indoor heat exchanger 110, and supplies the air that has passed through the indoor heat exchanger 110 to the room, which is the space to be air-conditioned. The configuration of the indoor heat exchanger 110 will be described in further detail below.

[0020] Next, the operation of each device in the air conditioner 1 will be described based on the flow of refrigerant. First, the operation of each device in the refrigerant circuit during heating operation will be described based on the flow of refrigerant. Solid arrows in FIG. 1 indicate the flow of refrigerant during heating operation. High-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the indoor heat exchanger 110. While passing through the indoor heat exchanger 110, the gas refrigerant condenses and liquefies by exchanging heat with, for example, the air in the space to be air-conditioned. The condensed and liquefied refrigerant passes through the expansion valve 240. The refrigerant is decompressed as it passes through the expansion valve 240. The refrigerant, which has been decompressed by the expansion valve 240 and is now in a two-phase gas-liquid state, passes through the outdoor heat exchanger 230. In the outdoor heat exchanger 230, the refrigerant evaporates by exchanging heat with outdoor air sent from the outdoor blower 250. The gasified refrigerant passes through the four-way valve 220 and is drawn back into the compressor 210. In this manner, the refrigerant in the air conditioner 1 circulates, and air conditioning related to heating is performed.

[0021] Next, cooling operation will be described. The dotted arrows in FIG. 1 indicate the flow of refrigerant during cooling operation. The high-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the outdoor heat exchanger 230. The refrigerant then passes through the outdoor heat exchanger 230, where it condenses and liquefies by exchanging heat with outdoor air supplied by the outdoor fan 250. The liquefied refrigerant then passes through the expansion valve 240. As it passes through the expansion valve 240, the refrigerant is reduced in pressure and assumes a two-phase gas-liquid state. The refrigerant, reduced in pressure by the expansion valve 240 and placed in a two-phase gas-liquid state, passes through the indoor heat exchanger 110. In the indoor heat exchanger 110, the refrigerant evaporates by exchanging heat with, for example, the air in the space to be air-conditioned. The gasified refrigerant then passes through the four-way valve 220 and is drawn back into the compressor 210. In this manner, the refrigerant in the air conditioner 1 circulates, performing air conditioning related to cooling. In the following description, it is assumed that the indoor heat exchanger 110 serves as an evaporator to perform cooling operation.

[0022] Fig. 2 is a diagram showing a schematic configuration of an example of a heat exchanger according to Embodiment 1. Here, the heat exchanger in Fig. 2 will be described as being the indoor heat exchanger 110, but the outdoor heat exchanger 230 is also assumed to have a similar configuration.

[0023] The indoor heat exchanger 110 is, for example, a fin-tube type heat exchanger. The indoor heat exchanger 110 has a heat exchanger body 111 that exchanges heat between the indoor air and the refrigerant. The heat exchanger body 111 is composed of multiple heat transfer tubes that form the refrigerant flow path and multiple fins that promote heat exchange between the refrigerant and the indoor air. One end of the heat exchanger body 111 is connected to a refrigerant distributor 112 via multiple capillary tubes 113, and the other end is connected to a header 114. The distributor 112 and the header 114 distribute or merge the refrigerant to the multiple heat transfer tubes of the heat exchanger body 111.

[0024] 2, a two-phase pipe temperature sensor 500 and a liquid pipe temperature sensor 510 are attached to the indoor heat exchanger 110. The two-phase pipe temperature sensor 500 and the liquid pipe temperature sensor 510 are detection devices that detect the temperature of the refrigerant at the attached position and send a signal related to the detection to the control device 400, which will be described later.

[0025] Two-phase pipe temperature sensor 500 detects the temperature of the refrigerant in the heat exchanger as the heat exchanger exit temperature. While not particularly limited, it is assumed here that two-phase pipe temperature sensor 500 is attached so as to detect the temperature of the refrigerant at a position approximately midway through the heat exchanger body 111. For example, two-phase pipe temperature sensor 500 is attached to a holder brazed to the U-shaped portion of a hairpin tube in heat exchanger body 111. Thus, the attachment position of two-phase pipe temperature sensor 500 is, for example, a position intended to detect the temperature of point P3 on the pH diagram in FIG. 4 (described later). Therefore, the heat exchanger exit temperature is typically the saturation temperature (evaporation temperature) of the refrigerant in a two-phase gas-liquid state during the evaporation process of the refrigeration cycle.

[0026] The liquid pipe temperature sensor 510 is a detection device that detects the temperature of the refrigerant flowing into and out of the indoor heat exchanger 110 as the liquid pipe temperature and sends a detection signal to the control device 400. The liquid pipe temperature sensor 510 detects the surface temperature of the outlet pipe of the heat exchanger functioning as a condenser. This temperature corresponds to the temperature of the liquid refrigerant after condensation. On the other hand, when the heat exchanger functions as an evaporator, the liquid pipe temperature sensor 510 detects the surface temperature of the inlet pipe of the heat exchanger. This temperature corresponds to the temperature of the two-phase refrigerant with a high wetness before evaporation. In this case, the liquid pipe temperature sensor 510 is a two-phase refrigerant temperature sensor that detects the temperature of the two-phase refrigerant with a high wetness, including the liquid refrigerant, flowing into the indoor heat exchanger 110, particularly when the indoor heat exchanger 110 functions as an evaporator. The liquid pipe temperature sensor 510 is attached to a position on the refrigerant flow path between the expansion valve 240 and the indoor heat exchanger 110 via the refrigerant piping 300. Here, the liquid pipe temperature sensor 510 is attached to a capillary tube 113 that connects the heat exchanger body 111 and the distributor 112. When the indoor heat exchanger 110 functions as a condenser, the liquid pipe temperature sensor 510 detects the temperature of the refrigerant flowing out from the indoor heat exchanger 110.

[0027] 3 is a diagram illustrating the configuration of the control device 400 in the air conditioner 1 according to embodiment 1. The control device 400 is a device that controls the air conditioner 1. Here, the outdoor unit 200 is described as having the control device 400, but this is not limited to this. Another unit may have the control device 400. Furthermore, the control device 400 may be a device independent of the unit that has the devices that make up the air conditioner 1.

[0028] The control device 400 has a control unit 410 and a storage unit 420. The control unit 410 has a control arithmetic processing device such as a CPU (Central Processing Unit) or a microcomputer. The control unit 410 in the first embodiment has, in particular, a determination unit 411, a correction unit 412, a dew detection unit 413, a correction unit 414, a correction unit 415, a correction unit 416, a correction unit 417, a correction unit 418, a correction unit 419, a correction unit 420, a correction unit 421, a correction unit 422, a correction unit 423, a correction unit 424, a correction unit 425, a correction unit 426, a correction unit 427, a correction unit 428, a correction unit 429, a correction unit 430, a correction unit 431, a correction unit 432, a correction unit restraint The determination unit 411 includes a control unit 413 and a circulation amount estimation unit 414. restraintFor this purpose, for example, the determination unit 411 has a correction determination unit 411A that determines the correction value (degree of correction) that the correction unit 412 applies to the heat exchanger passing temperature detected by the two-phase pipe temperature sensor 500. restraint The control unit 413 has a dew condensation determination unit 411B that determines whether or not to control dew condensation. The correction unit 412 corrects the heat exchanger passing temperature with a correction value based on the determination of the correction determination unit 411A. restraint When the dew formation determination unit 411B determines that dew formation will occur, the control unit 413 restraint Here, dew is restraint Dew formation performed by the control unit 413 restraint The content of the control is not particularly limited. For example, restraint The control unit 413 controls the compressor 210 to lower the drive frequency and the expansion valve 240 to increase the opening degree. restraint The control unit 413 restraint As a control, by controlling the compressor 210 to lower the driving frequency or by widening the opening of the expansion valve 240, the temperature of the refrigerant flowing on the low-pressure side in the refrigerant circuit, such as the evaporation temperature, can be raised, thereby making it possible to take early measures against condensation. restraint If condensation cannot be suppressed even by lowering the drive frequency of the compressor 210 or increasing the opening of the expansion valve 240, the control unit 413 may stop driving the compressor 210 or the operation of the air conditioner 1. Then, the circulation amount estimation unit 414 estimates the circulation amount of the refrigerant passing through the heat exchanger that serves as an evaporator. In the first embodiment, the circulation amount estimation unit 414 has a drive frequency acquisition unit 414A, and estimates the circulation amount based on the acquired drive frequency of the compressor 210.

[0029] The storage unit 420 also includes, for example, a volatile storage device (not shown) such as a random access memory (RAM) that can temporarily store data, and a non-volatile auxiliary storage device (not shown) such as a flash memory. Here, the storage unit 420 stores the relationship between the refrigerant circulation amount, the evaporation temperature in the evaporator, and the correction value as table-format data. It also stores data of a set threshold value used by the determination unit 411 when making a determination. The set threshold value, the correction value, and the like are set in advance by experimentation or the like depending on the refrigerant circulation amount and the evaporation temperature. The storage unit 420 also includes data in the form of a program that describes the processing procedures to be performed by the control arithmetic processing device. The control unit 410 then executes processing based on the program data. However, the present invention is not limited to this, and the control device 400 may also be a device (hardware) dedicated to control.

[0030] Figure 4 is a pH diagram for a refrigeration cycle system. The refrigerant temperature, which serves as the reference for determining the dryness state of the refrigerant, is the temperature at which the refrigerant passes through the heat exchanger, as detected by the two-phase pipe temperature sensor 500 described above. The two-phase pipe temperature sensor 500 is positioned to detect the refrigerant temperature at point P3 on the pH diagram (Mollier diagram) shown in Figure 4. A general characteristic of refrigerants is that the refrigerant pressure in the evaporator tends to decrease by the amount of pressure loss on the evaporator side (the low-pressure side of the refrigerant circuit) from point P3a, which is the refrigerant inlet of the evaporator, through point P3, to point P3b, which is the refrigerant outlet.

[0031] Fig. 5 is a diagram showing the relationship between pressure and temperature during the evaporation process of a non-azeotropic refrigerant mixture when the pressure inside the evaporator is constant in the refrigeration cycle apparatus of embodiment 1. Fig. 6 is a diagram showing the relationship between pressure and temperature during the evaporation process of a non-azeotropic refrigerant mixture when a pressure difference occurs inside the evaporator in the refrigeration cycle apparatus of embodiment 1. The arrows in Figs. 5 and 6 indicate the direction of refrigerant flow.

[0032] In the case of a non-azeotropic refrigerant mixture, the boiling points of the refrigerants involved in the mixture are different. Therefore, as enthalpy increases, the refrigerant temperature also increases. Therefore, as shown in FIG. 5, for example, when there is no or negligible pressure difference between point P3a and point P3b, the refrigerant temperature increases from the refrigerant inlet to the refrigerant outlet of the evaporator due to the physical properties of the non-azeotropic refrigerant mixture. Therefore, for a non-azeotropic refrigerant mixture, the liquid pipe temperature detected by liquid pipe temperature sensor 510 tends to be lower than the heat exchanger exit temperature detected by two-phase pipe temperature sensor 500. Furthermore, in the case of a non-azeotropic refrigerant mixture, even a refrigerant in a two-phase gas-liquid state during the evaporation process exhibits the same temperature trend as a refrigerant in a superheated state. For example, under normal conditions, a refrigerant in a two-phase gas-liquid state flows through the evaporator at point P3. However, if there is a refrigerant shortage in the refrigerant circuit due to a refrigerant leak or other reason, the refrigerant may already be in a superheated state at point P3. With a refrigerant with a temperature gradient, it may be difficult to distinguish this from a refrigerant shortage.

[0033] On the other hand, as shown in FIG. 6, if a pressure difference occurs between the refrigerant inlet and outlet of the evaporator due to pressure loss or other factors, the refrigerant temperature remains constant or decreases from the refrigerant inlet to the refrigerant outlet of the evaporator. Therefore, the refrigerant temperature decrease due to pressure loss and the temperature increase due to the physical properties of the non-azeotropic refrigerant mixture cancel each other out. FIG. 6 shows an example in which the refrigerant temperature decrease due to pressure loss and the temperature increase due to the physical properties of the non-azeotropic refrigerant mixture balance each other, resulting in a constant refrigerant temperature in the evaporator. As shown in FIGS. 5 and 6, for refrigerants with a temperature gradient, such as non-azeotropic refrigerants, the refrigerant temperature used to determine condensation is not uniform. Therefore, it is necessary to correct the refrigerant temperature using a correction value that corresponds to the pressure state within the evaporator. Therefore, in the control device 400 of the air conditioning apparatus 1 in embodiment 1, the correction unit 412 corrects the heat exchanger passing temperature based on the determination by the determination unit 411.

[0034] FIG. 7 is a diagram showing the change in refrigerant temperature over time in the indoor heat exchanger 110 of the air conditioner 1 according to Embodiment 1 when the refrigerant circulation rate is low. FIG. 8 is a diagram showing the change in refrigerant temperature over time in the indoor heat exchanger 110 of the air conditioner 1 according to Embodiment 1 when the refrigerant circulation rate is high. As described above, the air conditioner 1 performs cooling. Therefore, as described above, the indoor heat exchanger 110 functions as an evaporator. In the refrigerant circuit, the pressure difference generated within the evaporator varies depending on the amount of refrigerant circulating. When the amount of refrigerant circulating is high, the pressure loss is large, and when the amount of refrigerant circulating is low, the pressure loss is small. Therefore, as shown in FIG. 7, when the amount of refrigerant circulating is low and there is no or little pressure loss, the correction value that takes into account the temperature gradient for the temperature detected by the two-phase pipe temperature sensor 500 is large. On the other hand, as shown in FIG. 8, when an increase in the amount of refrigerant circulating causes a temperature drop due to pressure loss and a temperature rise due to the physical properties of the non-azeotropic refrigerant mixture, the correction value that takes into account the temperature gradient can be small.

[0035] As described above, according to the air conditioning apparatus 1 of the first embodiment, the determination unit 411 of the control device 400 determines a correction value for the heat exchanger passing temperature related to the temperature gradient based on the heat exchanger passing temperature detected by the two-phase pipe temperature sensor 500, and the correction unit 412 performs the correction. Then, the determination unit 411 of the control device 400 determines the condensation level based on the corrected heat exchanger passing temperature. restraint Determine whether to control the dew restraint The control unit 413 determines whether or not dew is present. restraint Therefore, the actual temperature passing through the heat exchanger detected by the two-phase pipe temperature sensor 500 can be corrected to a more accurate temperature. Therefore, the control device 400 of the air conditioner 1 can more accurately determine the temperature state of the refrigerant flowing on the low-pressure side of the refrigerant circuit, and can control the amount of condensation based on the determination. restraintIt is also possible to suppress or prevent condensation, freezing and frosting caused by dew or condensation around the air outlet through which air that has passed through the indoor heat exchanger 110 flows out of the indoor unit 100. Furthermore, in the air conditioner 1 of the first embodiment, the control device 400 can more accurately detect condensation and frost with a reduced number of temperature sensors based on the refrigerant temperature detected by the two-phase pipe temperature sensor 500. restraint It is possible to make decisions related to control.

[0036] Embodiment 2 FIG. 9 shows the condensation of the refrigeration cycle device according to the second embodiment. restraint 9 is a diagram illustrating control processing. The processing in FIG. 9 will be described as being performed by the control device 400 when the air conditioning device 1 is performing cooling operation. As described above, the circulation amount estimation unit 414 of the control device 400 has the drive frequency acquisition unit 414A. Therefore, the circulation amount estimation unit 414 estimates the refrigerant circulation amount based on the drive frequency of the compressor 210 (step S1). Here, the refrigerant circulation amount can generally be obtained based on the following equation (1):

[0037] Refrigerant circulation volume = volumetric efficiency x driving frequency x suction refrigerant density x displacement volume …(1)

[0038] In equation (1), the drive frequency is a term that affects the estimation of the refrigerant circulation amount. Therefore, in the second embodiment, when the circulation amount estimation unit 414 estimates the refrigerant circulation amount, the volumetric efficiency, the suction refrigerant density, and the displacement volume are assumed to be constant. Therefore, the refrigerant circulation amount can be calculated as an approximate value that depends on the drive frequency of the compressor 210.

[0039] In the determination unit 411 of the control device 400, the correction determination unit 411A of the determination unit 411 compares the estimated refrigerant circulation volume with a set threshold stored in the memory unit 420, and determines whether the refrigerant circulation volume is equal to or greater than the set threshold (step S2). The set threshold is set, for example, to a value that is 50% of the maximum refrigerant circulation volume of the refrigerant passing through the indoor unit 100. Here, if there are multiple indoor units 100, a set threshold is set for each maximum refrigerant circulation volume in each indoor unit 100. If the correction determination unit 411A determines that the refrigerant circulation volume is equal to or greater than the set threshold, the correction unit 412 corrects the heat exchanger passing temperature detected by the two-phase pipe temperature sensor 500 with a first correction value (step S3). Here, the first correction value also includes the case where no correction is performed (correction value = 0). Furthermore, if the correction determination unit 411A determines that the refrigerant circulation volume is smaller than the set threshold, the heat exchanger passing temperature detected by the two-phase pipe temperature sensor 500 is corrected by a second correction value greater than the first correction value (step S4). In some cases, the second correction value may be 0. Here, the temperature gradient varies depending on the evaporation temperature during operation. For example, when the evaporation temperature is 10°C, the temperature gradient of the azeotropic refrigerant mixture is 1.5 K, and when the evaporation temperature is 5°C, the temperature gradient of the azeotropic refrigerant mixture is 1.7 K. Therefore, the correction unit 412 performs correction using the first and second correction values ​​corresponding to the evaporation temperature. As described above, the first and second correction values ​​are stored as data in the storage unit 420.

[0040] Then, the dew condensation determination unit 411B of the determination unit 411 determines whether or not dew condensation has occurred based on the corrected temperature passing through the heat exchanger. restraint 7 and 8, the determination unit 411 determines whether or not to perform the control (step S5). setting If it is determined to be higher than the threshold, restraint The dew judging unit 411B judges that the control is not performed. restraint If it is determined that no control is to be performed, the process returns to step S1 and continues.

[0041] On the other hand, the dew condensation determination unit 411B restraint When it is determined that control is to be performed, restraint The control unit 413 restraint Control begins and dew restraint The process related to the control is performed (step S6). restraint The control unit 413 reduces the drive frequency of the compressor 210 or increases the opening of the expansion valve 240. Depending on the balance between the cooling capacity and the load, the temperature of the refrigerant on the low-pressure side of the refrigerant circuit may become low even if the drive frequency of the compressor 210 is reduced to the lower limit. Therefore, the dew condensation determination unit 411B of the determination unit 411 Dew Then, the condensation determination unit 411B determines whether the corrected temperature passing through the heat exchanger is condensation-free. setting If it is determined that the temperature is lower than the stop threshold, which is lower than the threshold, for example, the compressor 210 is stopped from operating, thereby further suppressing condensation. restraint Dew formation performed by the control unit 413 restraint As mentioned above, the content of the control is not particularly limited. restraint Control unit 413 is covered with dew restraint When the control is completed, the process returns to step S1 and continues.

[0042] As described above, the air conditioner 1 of embodiment 2 can achieve the effects described in embodiment 1. Furthermore, in the air conditioner 1 of embodiment 2, the control device 400 corrects the temperature passing through the heat exchanger based on the drive frequency. This makes it possible to easily obtain a more accurate refrigerant circulation amount.

[0043] Embodiment 3 FIG. 10 is a diagram showing the configuration of a control device 400 according to the third embodiment. In the components shown in FIG. 10, the components having the same reference numerals as those in FIG. 3 perform the same processing functions as those described in the first embodiment. The circulation amount estimation unit 414 of the control device 400 according to the third embodiment includes a suction temperature determination unit 414B. The suction temperature determination unit 414B determines the suction temperature of the refrigerant suctioned by the compressor 210 based on the heat exchanger exit temperature detected by the two-phase pipe temperature sensor 500 attached to the evaporator. The circulation amount estimation unit 414 according to the second embodiment estimates the refrigerant circulation amount based on the drive frequency of the compressor 210 and the suction density determined by the suction temperature determined by the suction temperature determination unit 414B.

[0044] As described in the first and second embodiments, the control device 400 determines and corrects the correction value based on the refrigerant circulation volume of the refrigerant circulating through the refrigerant circuit. Therefore, if the control device 400 can obtain a more accurate refrigerant circulation volume, it can perform a more accurate correction. Here, in the second embodiment, the circulation volume estimation unit 414 of the control device 400 estimated the refrigerant circulation volume by setting the suction refrigerant density to a constant value. The control device 400 in the third embodiment estimates the refrigerant circulation volume based not only on the drive frequency of the compressor 210 but also on the suction refrigerant density obtained from the suction temperature of the refrigerant sucked into the compressor 210.

[0045] As described above, according to the refrigeration cycle apparatus of the third embodiment, the control unit 410 of the control device 400 has the suction temperature determination unit 414B and determines the suction temperature based on the temperature passing through the heat exchanger. Therefore, the control device 400 can estimate the refrigerant circulation amount including the suction refrigerant density obtained from the suction temperature. Therefore, the control device 400 can more accurately estimate and determine the refrigerant circulation amount, and therefore more accurately determine the condensation. restraint It is possible to determine whether or not to perform control. When the refrigeration cycle apparatus of the third embodiment is the air conditioner 1 that conditions the air of a target space, it is possible to provide comfortable air conditioning for people in the room.

[0046] Embodiment 4 FIG. 11 is a diagram showing the configuration of a control device 400 according to the fourth embodiment. Among the components shown in FIG. 11, those with the same reference numerals as those in FIG. 3 perform the same processing functions as those described in the first embodiment. The control device 400 according to the fourth embodiment has a suction temperature estimation unit 414C. The suction temperature estimation unit 414C estimates the suction temperature of the refrigerant sucked into the compressor 210 based on the opening degree of the expansion valve 240. The circulation amount estimation unit 414 according to the fourth embodiment estimates the refrigerant circulation amount based on the drive frequency of the compressor 210 and the suction temperature estimated by the suction temperature estimation unit 414C.

[0047] In the refrigeration cycle apparatus of the fourth embodiment, the suction temperature estimation unit 414C in the control device 400 can obtain the Cv value of the expansion valve 240 based on the aperture of the expansion valve 240. The Cv value is a value determined by the type and port diameter of the expansion valve 240 and is a capacity coefficient of the valve. The Cv value is a numerical representation of the flow rate of a fluid passing through the valve at a certain differential pressure. The suction temperature estimation unit 414C also estimates the low-pressure pressure on the low-pressure side of the refrigerant circuit from the Cv value and the refrigerant circulation volume, and further estimates the suction temperature. The control device 400 can then estimate not only the drive frequency of the compressor 210 but also the refrigerant circulation volume based on the estimated suction temperature.

[0048] As described above, according to the refrigeration cycle apparatus of the fourth embodiment, the suction temperature estimation unit 414C of the control device 400 estimates the suction temperature based on the opening degree of the expansion valve 240, which expands high-pressure refrigerant and reduces the pressure to low-pressure refrigerant. This allows for a more accurate determination of the refrigerant circulation amount, enabling efficient control. Furthermore, when the refrigeration cycle apparatus of the fourth embodiment is an air conditioner 1 that conditions the air of a target space, it can provide comfortable air conditioning for people in the room.

[0049] Embodiment 5. In the third embodiment described above, the control unit 410 of the control device 400 has the suction temperature determination unit 414B, and in the fourth embodiment, the control unit 410 of the control device 400 has the suction temperature estimation unit 414C. However, the present invention is not limited to having only one of them. The control unit 410 of the control device 400 may be configured to have both the suction temperature determination unit 414B and the suction temperature estimation unit 414C and to perform the respective processes.

[0050] Furthermore, the refrigeration cycle apparatus of the first embodiment described above uses R454B refrigerant, a mixture of R32 refrigerant and R1234yf refrigerant in a ratio of 68.1:31.9, as the non-azeotropic refrigerant mixture circulating through the refrigerant circuit. However, this is not limited to this. For example, a non-azeotropic refrigerant mixture such as R407C may also be used. A near-azeotropic refrigerant mixture having a temperature gradient may also be used. Since the refrigeration cycle apparatus can be applied to various types of non-azeotropic refrigerant mixtures, refrigerants with low GWP can be used, resulting in a refrigeration cycle apparatus that takes the global environment into consideration. Furthermore, the refrigeration cycle apparatus can be configured to comply with regional market specifications and standards.

[0051] Furthermore, the configuration of the refrigerant circuit in the refrigeration cycle apparatus is not limited to the configuration of the air conditioner 1 in Fig. 1 described in the first embodiment above. For example, the refrigeration cycle apparatus may be configured to have an accumulator between the evaporator on the low-pressure side of the refrigerant circuit and the suction side of the compressor 210. The accumulator is a container that passes gas refrigerant and accumulates liquid refrigerant. The refrigeration cycle apparatus may also be configured to have a receiver between the heat exchanger that serves as a condenser on the high-pressure side of the refrigerant circuit and the expansion valve 240. The receiver is a container on the high-pressure side of the refrigerant circuit that accumulates excess refrigerant in the refrigerant circuit.

[0052] In the second embodiment described above, the control device 400 corrects the heat exchanger passage temperature using a first correction value or a second correction value based on the set threshold value, but this is not limited to this. The storage unit 420 may store a plurality of set threshold values ​​as data, divide the refrigerant circulation volume into three or more sections, and perform correction using a correction value corresponding to each section. In addition, if the relationship between the environmental state of the refrigerant during the evaporation process and the correction value can be expressed by a formula or the like, the correction value may be calculated by calculation or the like. [Industrial Applicability]

[0053] 2 is used as the indoor heat exchanger 110 of the indoor unit 100 in the first embodiment described above, but the present invention is not limited to this. The heat exchanger may be used as the outdoor heat exchanger 230 of the outdoor unit 200, or may be used as both the outdoor heat exchanger 230 and the indoor heat exchanger 110.

[0054] In the above-mentioned first embodiment and the like, the air conditioner 1 has been described, but the present invention can also be applied to other refrigeration cycle devices such as refrigerators and freezer devices. [Explanation of symbols]

[0055] 1 air conditioner, 100 indoor unit, 110 indoor heat exchanger, 111 heat exchanger body, 112 distributor, 113 capillary tube, 114 header, 120 indoor blower, 200 outdoor unit, 210 compressor, 220 four-way valve, 230 outdoor heat exchanger, 240 expansion valve, 250 outdoor blower, 300 refrigerant piping, 400 control device, 410 control unit, 411 determination unit, 411A correction determination unit, 411B Dew 412 correction unit; 413 dew restraint Control unit, 414 circulation amount estimation unit, 414A drive frequency acquisition unit, 414B suction temperature determination unit, 414C suction temperature estimation unit, 420 memory unit, 500 two-phase pipe temperature sensor, 510 liquid pipe temperature sensor.

Claims

1. A refrigeration cycle device having a refrigerant circuit configured by connecting a compressor, a condenser, an expansion valve, and an evaporator through pipes, which circulates a mixed refrigerant having a temperature gradient, a two-phase pipe temperature sensor for detecting a temperature of the mixed refrigerant passing through the evaporator at the time of passing through the heat exchanger; a control device that corrects the heat exchanger passing temperature detected by the two-phase pipe temperature sensor, determines whether or not to perform dew condensation suppression control based on the corrected temperature, and performs the dew condensation suppression control based on the determination; Equipped with The control device a circulation amount estimation unit including a drive frequency acquisition unit that acquires a drive frequency of the compressor and that estimates a refrigerant circulation amount of the mixed refrigerant based on the drive frequency; a correction determination unit that determines a correction value of the heat exchanger passing temperature detected by the two-phase pipe temperature sensor based on the estimated refrigerant circulation amount and a predetermined set threshold value; a correction unit that corrects the heat exchanger passing temperature based on the determination of the correction determination unit; A refrigeration cycle device having the same.

2. The circulation volume estimation unit The compressor further includes an intake temperature determination unit that determines an intake temperature of the compressor from the heat exchanger passing temperature detected by the two-phase pipe temperature sensor. The refrigeration cycle apparatus according to claim 1 , wherein the refrigerant circulation amount is estimated based on the drive frequency and the suction temperature.

3. The circulation volume estimation unit 3. The refrigeration cycle device according to claim 1, further comprising an intake temperature estimation unit that estimates an intake temperature of the compressor from an opening degree of the expansion valve, and that estimates the refrigerant circulation amount based on the drive frequency and the intake temperature.

4. 3. The refrigeration cycle device according to claim 1, wherein the mixed refrigerant having the temperature gradient is a non-azeotropic mixed refrigerant obtained by mixing an R32 refrigerant and an R1234yf refrigerant.

5. An air conditioner that cools and heats a target space using the refrigeration cycle device according to claim 1 or 2.

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