JP6463464B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus including a refrigerant circuit in which a refrigerant circulates.

  Some conventional refrigeration cycle apparatuses incorporate an internal heat exchanger that exchanges heat between the refrigerant flowing out of the condenser and the refrigerant flowing out of the evaporator. Conventionally, HFO-1234yf (R1234yf) or HFO-1234ze has been used as a refrigerant for circulating the refrigeration cycle apparatus. The internal heat exchanger is said to be useful for improving the refrigerating capacity when using a refrigerant such as HFO-1234yf (see, for example, Patent Document 1).

  Patent Document 1 includes a “compressor for compressing refrigerant, a condenser for condensing the compressed refrigerant, decompression / expansion means for decompressing / expanding the condensed refrigerant, and an evaporator for evaporating the decompressed / expanded refrigerant; In the refrigeration cycle including an internal heat exchanger that performs heat exchange between the condenser outlet side refrigerant and the evaporator outlet side refrigerant, R1234yf is used as the refrigerant, and the amount of heat exchange by the internal heat exchanger is The ratio of the heat exchange amount by the internal heat exchanger to the refrigeration capacity as a whole of the refrigeration capacity is set to 7% or more. Yes.

Japanese Patent No. 5180680

  However, the refrigeration cycle apparatus of Patent Document 1 is set so that the heat exchange amount in the internal heat exchanger is 7% or more of the refrigeration capacity of the entire apparatus. For this reason, since the length of the heat transfer part of the internal heat exchanger becomes long and the refrigerant pressure loss from the evaporator to the suction port of the compressor increases, there is a problem that the efficiency decreases.

  The present invention has been made to solve the above-described problems, and shortens the length of the heat transfer section of the internal heat exchanger when using HFO-1234yf or HFO-1234ze as the refrigerant, and is efficient. It aims at providing the refrigerating-cycle apparatus which aims at improvement.

The refrigeration cycle apparatus according to the present invention includes a refrigerant circuit in which a compressor, a condenser, a main expansion valve, and an evaporator are connected via a main pipe, a refrigerant that flows between the condenser and the main expansion valve, and evaporation Between the condenser and the internal heat exchanger, which exchanges heat between the refrigerant flowing between the compressor and the compressor and allows the refrigerant flowing out of the evaporator to flow into the suction side of the compressor A HIC heat exchanger connected in series to the internal heat exchanger, a bypass pipe that branches from between the condenser and the HIC heat exchanger, and leads the refrigerant to the compressor via the HIC heat exchanger, and condensation Based on the sub-expansion valve that depressurizes the refrigerant flowing into the bypass pipe from the condenser and flows out to the HIC heat exchanger, the state detection unit that detects the state of the refrigerant flowing through the refrigerant circuit, and the detection result by the state detection unit A control device for controlling the opening of the sub-expansion valve, and the HIC heat exchanger is And the refrigerant flowing through the main pipe from the condenser, and the refrigerant flowing through the auxiliary expansion valve from the condenser as it can heat exchange, the suction pressure state detection unit is a pressure of the refrigerant sucked into the compressor And a HIC outlet temperature sensor that detects an HIC outlet temperature that is a temperature of the refrigerant flowing out of the HIC heat exchanger, and the control device uses the result of detection by the state detector to detect the HIC A superheat degree calculation unit that calculates a first superheat degree that is a superheat degree at the outlet of the heat exchanger, and a valve control that controls the opening degree of the sub-expansion valve so that the first superheat degree falls within a preset target range. possess a part, the superheat calculation unit, first by subtracting on calculating the saturation temperature from the sensed suction pressure, the saturation temperature from the sensed HIC outlet temperature at HIC outlet temperature sensor in the pressure sensor and calculates the degree of superheat Than is.

  According to the present invention, the HIC heat exchanger connected in series to the internal heat exchanger is configured to exchange heat between the refrigerant flowing from the condenser through the main pipe and the refrigerant flowing from the condenser through the bypass pipe. Therefore, since the amount of heat exchange by the internal heat exchanger can be reduced, even when using HFO-1234yf or HFO-1234ze as the refrigerant, the length of the heat transfer portion of the internal heat exchanger is shortened, and Efficiency can be improved.

1 is a system configuration diagram including a refrigerant circuit diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. It is a Ph diagram which shows the operation state of the refrigerating-cycle apparatus of FIG. It is a flowchart which shows the control action at the time of the hot water supply driving | operation by the control apparatus of FIG. It is a characteristic view which shows the result of having simulated the relationship between the ratio of the heat exchange amount of an internal heat exchanger with respect to the total refrigerating capacity of the refrigerating-cycle apparatus of FIG. 1, and COP. It is a characteristic view which shows the relationship between the ratio of the heat exchange amount of an internal heat exchanger with respect to the total refrigerating capacity of the refrigerating-cycle apparatus of FIG. 1, and 1st superheat degree SHh of the exit of a HIC heat exchanger. It is a characteristic view which shows the relationship between the ratio of the heat exchange amount of a HIC heat exchanger with respect to the heat exchange amount of an internal heat exchanger in the refrigeration cycle apparatus of FIG. 1, and COP. It is a system block diagram including the refrigerant circuit figure of the refrigerating-cycle apparatus which concerns on Embodiment 2 of this invention. It is a Ph diagram which shows the operation state of the refrigeration cycle apparatus of FIG. It is a flowchart which shows the control action at the time of the hot water supply driving | operation by the control apparatus of FIG. It is a characteristic view which shows the result of having simulated the relationship between the ratio of the heat exchange amount of an internal heat exchanger with respect to the total refrigerating capacity of the refrigerating-cycle apparatus of FIG. 7, and COP. It is a characteristic view which shows the relationship between the ratio of the heat exchange amount of an internal heat exchanger with respect to the total refrigerating capacity of the refrigerating-cycle apparatus of FIG. 7, and 1st superheat degree SHh of the exit of a HIC heat exchanger. It is a characteristic view which shows the relationship between the ratio of the heat exchange amount of a HIC heat exchanger with respect to the heat exchange amount of an internal heat exchanger in the refrigeration cycle apparatus of FIG. 7, and COP.

Embodiment 1 FIG.
FIG. 1 is a system configuration diagram including a refrigerant circuit diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. FIG. 1 shows a state when a heating operation for raising the temperature of water on the load side is performed.

  The refrigeration cycle apparatus 100 according to the first embodiment is configured such that the compressor 10, the four-way valve 20, the condenser 30, the main expansion valve 80, and the evaporator 60 are connected in an annular shape. In the refrigeration cycle apparatus 100, a HIC (Heat InterChanger) heat exchanger 50 and an internal heat exchanger 70 connected in series are disposed between the condenser 30 and the main expansion valve 80. That is, the refrigeration cycle apparatus 100 includes a refrigerant circuit in which the compressor 10, the condenser 30, the main expansion valve 80, and the evaporator 60 are connected via the main pipe 1, and between the condenser 30 and the main expansion valve 80. Heat exchange between the refrigerant flowing through the evaporator 60 and the refrigerant flowing between the evaporator 60 and the compressor 10, and an internal heat exchanger 70 that causes the refrigerant flowing out of the evaporator to flow into the suction side of the compressor 10, and a condenser 30 and an internal heat exchanger 70, and an HIC heat exchanger 50 connected in series to the internal heat exchanger 70.

  The refrigeration cycle apparatus 100 is a main pipe that circulates refrigerant to the compressor 10, the four-way valve 20, the condenser 30, the HIC heat exchanger 50, the internal heat exchanger 70, the main expansion valve 80, and the evaporator 60 as refrigerant pipes. 1 The refrigeration cycle apparatus 100 includes a bypass pipe 2 that branches from between the condenser 30 and the HIC heat exchanger 50 and guides the refrigerant to the compressor 10 via the HIC heat exchanger 50. The bypass pipe 2 branches from the main pipe 1 extending from the outlet of the condenser 30 and bypasses part of the high-pressure liquid refrigerant that has flowed out of the condenser 30 to flow into the main pipe 1. The main pipe 1 extending from 70 is connected. Furthermore, the refrigeration cycle apparatus 100 has a sub-expansion valve 40 that decompresses the refrigerant flowing into the bypass pipe 2 from the condenser 30 and flows out to the HIC heat exchanger 50. That is, the bypass pipe 2 is configured to bypass a part of the high-pressure liquid refrigerant that has passed through the condenser 30 and pass the sub expansion valve 40 and the HIC heat exchanger 50.

  More specifically, the compressor 10 is composed of, for example, an inverter compressor whose capacity can be controlled, and sucks and compresses a low-temperature and low-pressure gas refrigerant, and discharges it in a state of a high-temperature and high-pressure gas refrigerant. The four-way valve 20 switches the direction between the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 and the low-temperature and low-pressure gas refrigerant sucked into the compressor 10. The condenser 30 is composed of, for example, a plate heat exchanger, and heats the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 and passing through the four-way valve 20 by heat exchange with water.

  The sub-expansion valve 40 is disposed in the bypass pipe 2 and depressurizes the high-pressure liquid refrigerant that has passed through the condenser 30 to form a low-pressure two-phase refrigerant. The HIC heat exchanger 50 exchanges heat between the high-pressure liquid refrigerant that has flowed out of the condenser 30 and passed through the main pipe 1, and the low-pressure two-phase refrigerant that has been decompressed by the sub-expansion valve 40. The evaporator 60 includes, for example, a fin plate heat exchanger and the like, and evaporates the refrigerant by exchanging heat with air. The internal heat exchanger 70 has, for example, a double pipe, and exchanges heat between the high-pressure liquid refrigerant that has passed through the HIC heat exchanger 50 and the low-pressure gas refrigerant that has passed through the evaporator 60. The main expansion valve 80 decompresses the high-pressure liquid refrigerant that has passed through the internal heat exchanger 70 into a low-pressure two-phase refrigerant.

  In the refrigeration cycle apparatus 100, a refrigerant circuit is formed in which the refrigerant is circulated sequentially to the compressor 10, the condenser 30, the sub-expansion valve 40, the HIC heat exchanger 50, the internal heat exchanger 70, the main expansion valve 80, and the evaporator 60. Has been. The refrigeration cycle apparatus 100 uses a mixed refrigerant containing HFO-1234yf or HFO-1234ze as a refrigerant.

  HFO-1234yf or HFO-1234ze as a refrigerant has a global warming potential (GWP) of 4. On the other hand, the GWP of R410A conventionally used is 2090, and the GWP of R407C is 1770. That is, HFO-1234yf or HFO-1234ze is a refrigerant having a smaller influence on the global environment than R410A and R407C.

  In addition, HFO-1234yf or HFO-1234ze has the characteristic that the discharge temperature from the compressor 10 is hard to rise compared with R410A and R407C. In addition, in the case of heating operation for increasing the temperature of water, HFO-1234yf or HFO-1234ze decreases the condensation pressure when the discharge temperature is increased by increasing the suction superheat degree of the compressor 10, The efficiency is improved.

  Next, the operation of the hot water supply operation of the refrigeration cycle apparatus 100 will be described with reference to FIGS. 1 and 2. FIG. 2 is a Ph diagram showing the operating state of the refrigeration cycle apparatus 100, wherein the vertical axis represents the refrigerant absolute pressure P [MPa · abs], and the horizontal axis represents the specific enthalpy h [kJ / kg]. .

  A refrigerant in a low-temperature and low-pressure gas state is sucked into the compressor 10 (C01: compressor 10 suction port), compressed by the compressor 10, and discharged as a high-temperature and high-pressure gas. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the condenser 30 via the four-way valve 20. The high-temperature high-pressure gas refrigerant that has flowed into the condenser 30 radiates heat to the heat exchange medium, and becomes high-pressure liquid refrigerant. The high-pressure liquid refrigerant that has flowed out of the condenser 30 (C02: outlet of the condenser 30) branches in two directions. One branched high-pressure liquid refrigerant flows into the sub-expansion valve 40 through the bypass pipe 2 and is decompressed and expanded to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (C03: sub-expansion valve 40 outlet). The other branched high-pressure liquid refrigerant flows into the HIC heat exchanger 50 and exchanges heat with the low-temperature and low-pressure gas-liquid two-phase refrigerant that has flowed out of the sub-expansion valve 40 (T01) to become a high-pressure supercooled liquid refrigerant. Outflow (C04a: HIC heat exchanger 50 outlet). The low-temperature and low-pressure gas-liquid two-phase refrigerant that has flowed out of the sub-expansion valve 40 exchanges heat with the high-pressure liquid refrigerant that has flowed into the HIC heat exchanger 50 (T01), and flows out as medium-temperature and low-pressure gas refrigerant (C04b: HIC heat). Exchanger 50 outlet).

  The high-pressure supercooled liquid refrigerant that has flowed out of the HIC heat exchanger 50 flows into the internal heat exchanger 70, exchanges heat with the low-pressure and low-temperature gas refrigerant that has flowed out of the evaporator 60 and passed through the four-way valve 20 (T02), Further, it flows out as a liquid refrigerant having a high degree of supercooling (C05: outlet of internal heat exchanger 70). The supercooled liquid refrigerant that has flowed out of the internal heat exchanger 70 flows into the main expansion valve 80, is decompressed and expanded to become a low-pressure two-phase refrigerant, and flows into the evaporator 60 (C06: evaporator 60 inlet). The low-pressure two-phase refrigerant that has flowed into the evaporator 60 cools the air that is the heat exchange medium, evaporates, and flows out as a low-temperature and low-pressure gas refrigerant (C07: outlet of the evaporator 60).

  The low-temperature and low-pressure gas refrigerant that has flowed out of the evaporator 60 passes through the four-way valve 20 again, and then flows into the internal heat exchanger 70 and exchanges heat with the high-pressure liquid refrigerant that has flowed out of the HIC heat exchanger 50 (T02). Then, it flows out as medium temperature and low pressure gas refrigerant (C08: internal heat exchanger 70 outlet). The medium-temperature low-pressure gas refrigerant that has flowed out of the internal heat exchanger 70 joins the medium-temperature low-pressure gas refrigerant that has flowed out of the HIC heat exchanger 50, becomes low-pressure gas with a large degree of superheat, and is sucked back into the compressor 10 (C01: Compressor 10 inlet).

  Since the low-pressure gas before being sucked into the compressor 10 flows on the suction side of the compressor 10 of the internal heat exchanger 70, the increase in the length of the heat transfer section increases the low-pressure pressure loss. This is a factor that deteriorates the efficiency of the refrigeration cycle apparatus 100. On the other hand, since a small amount of two-phase refrigerant that bypasses the suction pipe of the compressor 10 flows through the bypass pipe 2 that is the gas side of the HIC heat exchanger 50, there is no influence on the efficiency of the refrigeration cycle apparatus 100 due to pressure loss. Therefore, according to the refrigeration cycle apparatus 100 having the HIC heat exchanger 50, the length of the heat transfer section of the internal heat exchanger 70 can be shortened and efficiency can be improved. In addition, the HIC heat exchanger 50 can be configured with a narrower pipe than the internal heat exchanger 70, and can have a compact configuration.

  Next, the control configuration of the refrigeration cycle apparatus 100 will be described with reference to FIG. The refrigeration cycle apparatus 100 includes a state detection unit that detects the state of the refrigerant flowing through the refrigerant circuit, and a microcomputer such as a DSP, for example. And a control device 90 for controlling the opening degree. The state detection unit detects the pressure sensor 110 that detects the suction pressure Ps that is the pressure of the gas refrigerant sucked into the compressor 10 and the HIC outlet temperature Tho that is the temperature of the gas refrigerant that flows out of the HIC heat exchanger 50. The HIC outlet temperature sensor 120 and the evaporator outlet temperature sensor 130 for detecting the evaporator outlet temperature The which is the temperature of the gas refrigerant flowing out of the evaporator 60 are provided.

  The control device 90 has a superheat degree calculation unit 90a that calculates a first superheat degree that is a superheat degree at the outlet of the HIC heat exchanger 50 using a result of detection by the state detection part, and a first superheat degree is preset. A valve control unit 90c for controlling the opening degree of the sub-expansion valve 40 so as to be within the target range.

  More specifically, the control device 90 calculates the saturation temperature f (Ps) of the suction pressure Ps detected by the pressure sensor 110 and calculates the saturation temperature f (Ps) from the HIC outlet temperature Tho detected by the HIC outlet temperature sensor 120. ) Is subtracted to calculate a first superheat degree SHa that calculates the first superheat degree SHh that is the degree of heating of the gas outlet of the HIC heat exchanger 50, and the first superheat degree SHh calculated in the superheat degree calculator 90a, A superheat degree determination unit 90b that compares a first set value that is a preset allowable lower limit and determines whether or not the first superheat degree SHh is less than the first set value, and a determination by the superheat degree determination unit 90b And a valve control unit 90c that controls the opening degree of the sub-expansion valve 40 and the main expansion valve 80.

  When it is determined that the first superheat degree SHh is equal to or greater than the first set value, the superheat degree determination unit 90b compares the first superheat degree SHh with a second set value that is a preset allowable upper limit, 1 has a function of determining whether the degree of superheat SHh is greater than the second set value. The valve control unit 90c is configured to reduce the opening degree of the sub-expansion valve 40 when the superheat degree determination unit 90b determines that the first superheat degree SHh is less than the first set value. Further, the valve control unit 90c increases the opening degree of the sub-expansion valve 40 when the superheat degree determination unit 90b determines that the first superheat degree SHh is larger than the second set value. And the valve control part 90c maintains the opening degree of the sub expansion valve 40, when it determines with 1st superheat degree SHh being below 2nd setting value in the superheat degree determination part 90b. That is, in the first embodiment, the target range is set to a range that is not less than the first set value and not more than the second set value.

  Further, the superheat degree calculation unit 90 a subtracts the saturation temperature f (Ps) of the suction pressure Ps from the evaporator outlet temperature The detected by the evaporator outlet temperature sensor 130 to obtain the superheat degree at the outlet of the evaporator 60. It has a function of calculating the second superheat degree SHe. The superheat degree determination unit 90b compares the second superheat degree SHe calculated by the superheat degree calculation unit 90a with a preset third set value (target value), and the second superheat degree SHe is the third set value. It has a function to determine whether or not it is less than. The valve control unit 90c reduces the opening degree of the main expansion valve 80 when the second superheat degree determination unit 90b determines that the second superheat degree SHe is less than the third set value, and the second superheat degree SHe is When it is determined that the value is greater than or equal to the third set value, the opening of the main expansion valve 80 is increased. That is, the valve control unit 90c controls the opening degree of the main expansion valve 80 so that the second superheat degree SHe becomes the sixth set value that is the target value.

  Next, with reference to FIG.1 and FIG.3, the procedure of the opening / closing control of the main expansion valve 80 and the sub expansion valve 40 by the control apparatus 90 at the time of hot water supply operation is demonstrated. FIG. 3 is a flowchart showing a control operation during hot water supply operation by the control device 90.

  First, the superheat degree calculation unit 90a inputs the suction pressure Ps detected by the pressure sensor 110 (FIG. 3: step S101), and inputs the HIC outlet temperature Tho detected by the HIC outlet temperature sensor 120 (FIG. 3: Step S102). The superheat degree calculation unit 90a calculates the saturation temperature f (Ps) of the suction pressure Ps, subtracts the calculated f (Ps) from the HIC outlet temperature Tho, and the first superheat degree at the gas outlet of the HIC heat exchanger 50. SHh is calculated (FIG. 3: step S103).

  The superheat degree determination unit 90b compares the first superheat degree SHh calculated by the superheat degree calculation unit 90a with the first set value, and determines whether or not the first superheat degree SHh is less than the first set value. (FIG. 3: Step S104). When the superheat degree determination unit 90b determines that the first superheat degree SHh is less than the first set value (FIG. 3: Step S104 / Yes), the valve control unit 90c determines the opening degree of the sub expansion valve 40. The heat exchange amount of the HIC heat exchanger 50 is reduced (FIG. 3: Step S105). On the other hand, when the superheat degree determination unit 90b determines that the first superheat degree SHh is greater than or equal to the first set value (FIG. 3: step S104 / No), the valve control unit 90c determines that the first superheat degree SHh is the first superheat degree SHh. The second set value is compared to determine whether or not the first superheat degree SHh is greater than the second set value (FIG. 3: step S106).

  Next, the superheat degree determination unit 90b compares the first superheat degree SHh calculated by the superheat degree calculation unit 90a with the second set value, and determines whether the first superheat degree SHh is larger than the second set value. Determination is made (FIG. 3: step S106). When the superheat degree determination unit 90b determines that the first superheat degree SHh is larger than the second set value (FIG. 3: Step S106 / Yes), the valve control unit 90c increases the opening degree of the sub expansion valve 40. Then, the heat exchange amount of the HIC heat exchanger 50 is increased (FIG. 3: step S107). On the other hand, when the superheat degree determination unit 90b determines that the first superheat degree SHh is equal to or less than the second set value (FIG. 3: Step S106 / No), the valve control unit 90c presents the current sub-expansion valve. The opening degree of 40 is maintained (FIG. 3: Step S108). That is, the valve control unit 90c controls the opening degree of the sub-expansion valve 40 so that the first degree of superheat falls within a target range that is not less than the first set value and not more than the second set value.

  Next, the superheat degree calculation unit 90a inputs the evaporator outlet temperature The detected by the evaporator outlet temperature sensor 130 (FIG. 3: step S109). The superheat degree calculation unit 90a calculates the second superheat degree SHe at the outlet of the evaporator 60 by subtracting the saturation temperature f (Ps) of the suction pressure Ps from the evaporator outlet temperature The input from the evaporator outlet temperature sensor 130. (FIG. 3: Step S110). The superheat degree determination unit 90b compares the second superheat degree SHe calculated by the superheat degree calculation unit 90a with the third set value, and determines whether the second superheat degree SHe is less than the third set value. (FIG. 3: Step S111).

  The valve control unit 90c determines the degree of opening of the main expansion valve 80 when the superheat degree determination unit 90b determines that the second superheat degree SHe is less than the third set value (FIG. 3: Step S111 / Yes). The heat exchange amount of the evaporator 60 is suppressed by reducing the size (FIG. 3: Step S112). On the other hand, the valve control unit 90c opens the main expansion valve 80 when the superheat degree determination unit 90b determines that the second superheat degree SHe is equal to or greater than the third set value (FIG. 3: step S111 / No). The degree is increased and the heat exchange amount of the evaporator 60 is increased (FIG. 3: step S113).

  FIG. 4 is a characteristic diagram showing a simulation result of the relationship between the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity of the refrigeration cycle apparatus 100 (hereinafter simply referred to as “total refrigeration capacity”) and COP. is there. With reference to FIG. 4, the area | region where COP (Coefficient of Performance: Performance coefficient) of the refrigerating-cycle apparatus 100 takes a favorable value is demonstrated. In the case of FIG. 4, the peak value is obtained when the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is about 4%. If the length of the heat transfer section of the internal heat exchanger 70 is too short (if the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is smaller than a predetermined lower limit amount), the suction superheat degree of the compressor 10 is increased. The COP is reduced because the discharge temperature of the compressor 10 is reduced and the increase in the discharge temperature is reduced. On the other hand, when the length of the heat transfer portion of the internal heat exchanger 70 is too long (when the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is greater than a predetermined upper limit amount), the internal heat exchanger 70 The refrigerant pressure loss on the low-pressure gas side increases and COP decreases.

  As shown in FIG. 4, in the refrigeration cycle apparatus 100, if the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is in the range of 2.4% or more and less than 7%, the COP takes a good value. Can drive in the area. In the first embodiment, a region where COP takes a good value is a region where COP is 100% or more. That is, the refrigeration cycle apparatus 100 sets the length of the heat transfer portion of the internal heat exchanger 70 so that the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is 2.4% or more and less than 7%. It is set.

  FIG. 5 is a characteristic diagram showing the relationship between the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity and the first superheat degree SHh at the outlet of the HIC heat exchanger 50. With reference to FIG. 5, the adjustment method of the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity will be described. As shown in FIG. 5, by controlling the first superheat degree SHh at the outlet of the HIC heat exchanger 50, the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity can be controlled. In the first embodiment, the first lower limit of the first superheat degree SHh is set so that the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is in the range of 2.4% or more and less than 7%. The set value is set to 15 ° C., and the second set value that is the allowable upper limit of the first superheat degree SHh is set to 44 ° C. That is, the valve control unit 90c is configured to control the opening degree of the sub expansion valve 40 so that the first superheat degree SHh becomes a value within the target range.

  FIG. 6 is a characteristic diagram showing the relationship between the ratio of the heat exchange amount of the HIC heat exchanger 50 to the heat exchange amount of the internal heat exchanger 70 and the COP in the refrigeration cycle apparatus 200. With reference to FIG. 6, the relationship between the heat exchange amount of the HIC heat exchanger 50 and the internal heat exchanger 70 and the region where the COP of the refrigeration cycle apparatus 100 takes a good value will be described.

  Regarding the refrigerant flow during the heating operation, since the HIC heat exchanger 50 is on the upstream side and the internal heat exchanger 70 is on the downstream side, if the heat exchange amount of the HIC heat exchanger 50 is increased, the internal heat exchanger 50 The temperature of the high-pressure liquid refrigerant flowing into 70 decreases. That is, as the heat exchange amount of the HIC heat exchanger 50 increases, the heat exchange amount of the internal heat exchanger 70 decreases, and as shown in FIG. There is a peak value of COP with respect to the ratio of the heat exchange amount of the exchanger 50.

  In the first embodiment, the ratio of the heat exchange amount of the HIC heat exchanger 50 to the heat exchange amount of the internal heat exchanger 70 is set to be 160% or more and 700% or less. With this setting, the refrigeration cycle apparatus 100 can be operated in a region where the COP takes a good value as shown in FIG.

  As described above, the refrigeration cycle apparatus 100 according to the first embodiment includes the HIC heat exchanger 50 connected in series to the internal heat exchanger 70, and the HIC heat exchanger 50 is connected to the main heat exchanger 50 from the condenser 30. A configuration is adopted in which heat exchange is performed between the high-pressure refrigerant flowing in through the pipe 1 and the two-phase refrigerant flowing in from the condenser 30 via the sub-expansion valve 40 on the bypass pipe 2. For this reason, since the amount of heat exchange by the internal heat exchanger 70 can be reduced, the length of the heat transfer portion of the internal heat exchanger 70 that causes the refrigerant pressure loss on the suction side of the compressor 10 is more than necessary. The operation in the region where the COP is high can be realized without increasing the length. That is, according to the refrigeration cycle apparatus 100, the amount of heat exchange by the internal heat exchanger 70 can be reduced. Therefore, even when HFO-1234yf or HFO-1234ze is used as the refrigerant, heat transfer of the internal heat exchanger 70 is achieved. The length of the part can be shortened and the efficiency can be improved. In addition, since the valve control unit 90c employs a configuration in which the opening degree of the main expansion valve 80 is controlled so that the second superheat degree becomes a preset target value (third set value), the secondary expansion is performed. The influence of the control of the valve 40 on the evaporator 60 side can be minimized.

  Conventionally, since the internal heat exchanger has a long double tube configuration, there is a problem that productivity is lowered. However, in the refrigeration cycle apparatus 100, the length of the heat transfer section of the internal heat exchanger 70 is long. Therefore, productivity can be improved. Furthermore, since the bypass pipe 2 passing through the HIC heat exchanger 50 is configured to flow a small amount of two-phase refrigerant, the influence of the pressure loss on the efficiency of the refrigeration cycle apparatus 200 is suppressed. Therefore, according to the refrigeration cycle apparatus 200 having the HIC heat exchanger 50, the length of the heat transfer section of the internal heat exchanger 70 can be shortened and efficiency can be improved. In addition, since the HIC heat exchanger 50 can be configured with a narrower pipe than the internal heat exchanger 70, the apparatus can be made compact. Furthermore, by using a thin pipe for the HIC heat exchanger 50 and making it more compact, the dimensions of the equipment can be made smaller than in the conventional configuration, improving installation, reducing equipment weight, and reducing costs. Can be realized.

  In addition, since the refrigeration cycle apparatus 100 of the first embodiment is configured to use HFO-1234yf or HFO-1234ze having a low global warming potential, it is possible to reduce the influence on the global environment. .

Embodiment 2. FIG.
Next, the configuration and operation of the refrigeration cycle apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 7 is a system configuration diagram including a refrigerant circuit diagram of the refrigeration cycle apparatus 200 according to the second embodiment. FIG. 7 shows a state when a heating operation for increasing the temperature of water on the load side is performed. The same reference numerals are used for the same constituent members as those in the first embodiment.

  The refrigeration cycle apparatus 200 includes, for example, a capacity-controllable inverter compressor and the like, and includes a compressor 15 that sucks low-temperature low-pressure gas refrigerant, compresses it, and discharges it into a high-temperature high-pressure gas refrigerant state. The compressor 15 has an injection port (not shown) and an intermediate chamber (not shown) for injecting an intermediate pressure refrigerant (intermediate pressure refrigerant) flowing into the bypass pipe 2 and flowing out of the HIC heat exchanger 50 in the compression process. have. That is, the gas refrigerant flowing out of the HIC heat exchanger 50 is injected into an intermediate chamber provided in the pressure chamber of the compressor 15 through the injection port.

  Next, the operation of the hot water supply operation of the refrigeration cycle apparatus 200 will be described with reference to FIGS. FIG. 8 is a Ph diagram illustrating the operating state of the refrigeration cycle apparatus 200, wherein the vertical axis represents the refrigerant absolute pressure P [MPa · abs], and the horizontal axis represents the specific enthalpy h [kJ / kg]. .

  The refrigerant in the low-temperature and low-pressure gas state (C11: outlet of the internal heat exchanger 70) is sucked into the compressor 15, compressed by the compressor 15, and discharged as a high-temperature and high-pressure gas. The high-temperature and high-pressure gas refrigerant discharged from the compressor 15 flows into the condenser 30 via the four-way valve 20. The high-temperature high-pressure gas refrigerant that has flowed into the condenser 30 radiates heat to the heat exchange medium, and becomes high-pressure liquid refrigerant. The high-pressure liquid refrigerant that has flowed out of the condenser 30 (C12: outlet of the condenser 30) branches in two directions. One of the branched high-pressure liquid refrigerant flows into the sub-expansion valve 40 through the bypass pipe 2 and is decompressed and expanded to become a gas-liquid two-phase refrigerant of medium temperature and medium pressure (C13: sub-expansion valve 40 outlet). The other branched high-pressure liquid refrigerant flows into the HIC heat exchanger 50 and exchanges heat with the medium-temperature and medium-pressure gas-liquid two-phase refrigerant that has flowed out of the sub-expansion valve 40 (T11) to become a high-pressure supercooled liquid refrigerant. (C14a: HIC heat exchanger 50 outlet). The medium-temperature and medium-pressure gas-liquid two-phase refrigerant that has flowed out of the sub-expansion valve 40 exchanges heat with the high-pressure liquid refrigerant that has flowed into the HIC heat exchanger 50 (T11) to become heated gas (C14b: HIC heat exchanger 50 outlet). Then, it is injected into the intermediate pressure of the compressor 15 (C15: intermediate pressure merging section).

  The high-pressure supercooled liquid refrigerant that has flowed out of the HIC heat exchanger 50 flows into the internal heat exchanger 70, exchanges heat with the low-pressure and low-temperature gas refrigerant that has flowed out of the evaporator 60 and passed through the four-way valve 20 (T12), Furthermore, it flows out as a liquid refrigerant with a large degree of supercooling (C16: outlet of internal heat exchanger 70). The supercooled liquid refrigerant that has flowed out of the internal heat exchanger 70 flows into the main expansion valve 80, is decompressed and expanded to become a low-pressure two-phase refrigerant, and flows into the evaporator 60 (C17: internal heat exchanger 70 inlet). The low-pressure two-phase refrigerant that has flowed into the evaporator 60 cools the air that is the heat exchange medium, evaporates, and flows out as a low-temperature and low-pressure gas refrigerant (C18: outlet of the evaporator 60).

  The low-temperature and low-pressure gas refrigerant that has flowed out of the evaporator 60 passes through the four-way valve 20 again, then flows into the internal heat exchanger 70, and exchanges heat with the high-pressure liquid refrigerant that has flowed out of the HIC heat exchanger 50 (T12). ), A gas refrigerant having a high degree of superheat, and sucked into the compressor 15 again.

  Since the low-pressure gas before being sucked into the compressor 10 flows through the main pipe 1 on the gas side of the internal heat exchanger 70, the low-pressure pressure loss increases as the pipe length increases, and the refrigeration cycle apparatus 200 It becomes a factor to deteriorate efficiency. On the other hand, since a small amount of two-phase refrigerant that bypasses the suction side of the compressor 10 flows through the bypass pipe 2 that is the gas side of the HIC heat exchanger 50, there is no influence on the efficiency of the refrigeration cycle apparatus 200 due to pressure loss. Therefore, the HIC heat exchanger 50 can be configured with a narrower pipe than the internal heat exchanger 70, and can have a compact configuration.

  Next, the control configuration of the refrigeration cycle apparatus 200 will be described with reference to FIG. The refrigeration cycle apparatus 200 includes a state detection unit that detects the state of the refrigerant flowing through the refrigerant circuit, and a control device 190 that controls the opening degrees of the sub-expansion valve 40 and the main expansion valve 80 based on the detection result of the state detection unit. And have. The state detection unit of the second embodiment includes a pressure sensor 110 that detects the suction pressure Ps that is the pressure of the gas refrigerant sucked into the compressor 10, and the HIC that is the temperature of the gas refrigerant that flows out of the HIC heat exchanger 50. The HIC outlet temperature sensor 120 that detects the outlet temperature Th, the HIC inlet temperature sensor 210 that detects the HIC inlet temperature Thi, which is the temperature of the gas refrigerant flowing into the HIC heat exchanger 50, and the internal heat exchanger 70 A suction temperature sensor 230 that detects a suction temperature Ts that is a temperature of a gas refrigerant sucked into the compressor 15, a pressure sensor 110, an HIC outlet temperature sensor 120, and an HIC inlet temperature sensor 210 are provided.

  The control device 190 subtracts the HIC inlet temperature Thi detected by the HIC inlet temperature sensor 210 from the HIC outlet temperature Th detected by the HIC outlet temperature sensor 120, and determines the degree of superheat of the gas outlet of the HIC heat exchanger 50. A superheat degree calculation unit 190a for calculating a certain first superheat degree SHh, the first superheat degree SHh calculated in the superheat degree calculation unit 190a, and a fourth set value that is a preset allowable lower limit are compared, Based on the results of the determination by the superheat degree determination unit 190b and the superheat degree determination unit 190b that determine whether or not the one superheat degree SHh is less than the fourth set value, the sub-expansion valve 40 and the main expansion valve 80 are opened. And a valve control unit 190c for controlling the degree.

  When it is determined that the first superheat degree SHh is equal to or greater than the fourth set value, the superheat degree determination unit 190b compares the first superheat degree SHh with the fifth set value that is a preset allowable upper limit, It has a function of determining whether or not 1 superheat degree SHh is larger than the fifth set value. The valve control unit 190c reduces the opening degree of the sub-expansion valve 40 when the superheat degree determination unit 190b determines that the first superheat degree SHh is less than the fourth set value. The valve control unit 190c increases the opening degree of the sub-expansion valve 40 when the superheat degree determination unit 190b determines that the first superheat degree SHh is larger than the fifth set value. And the valve control part 190c maintains the opening degree of the sub expansion valve 40, when it determines with 1st superheat degree SHh being below 5th setting value in the superheat degree determination part 190b. That is, in the second embodiment, the target range is set to a range that is not less than the fourth set value and not more than the fifth set value.

  Further, the superheat degree calculation unit 190a calculates the saturation temperature f (Ps) of the suction pressure Ps detected by the pressure sensor 110, and subtracts the saturation temperature f (Ps) from the suction temperature Ts detected by the suction temperature sensor 230. Thus, the third superheat degree SHs that is the superheat degree of the suction port of the compressor 15 is calculated. The superheat degree determination unit 190b compares the third superheat degree SHs calculated by the superheat degree calculation unit 190a with a preset sixth set value (target value), and the third superheat degree SHs is the sixth set value. It has a function to determine whether or not it is less than. When the superheat determination unit 190b determines that the third superheat degree SHs is less than the sixth set value, the valve control unit 190c reduces the opening of the main expansion valve 80, and the third superheat degree SHs When it is determined that the value is equal to or larger than the sixth set value, the opening degree of the main expansion valve 80 is increased. That is, the valve control unit 190c controls the opening degree of the main expansion valve 80 so that the third superheat degree SHs becomes the sixth set value that is the target value.

  Next, with reference to FIG. 7 and FIG. 9, the procedure of the opening / closing control of the main expansion valve 80 and the sub expansion valve 40 by the control device 190 during the hot water supply operation will be described. FIG. 9 is a flowchart showing a control operation during hot water supply operation by control device 190.

  First, the superheat degree calculation unit 190a inputs the HIC inlet temperature Thi detected by the HIC inlet temperature sensor 210 (FIG. 9: Step S201), and inputs the HIC outlet temperature Tho detected by the HIC outlet temperature sensor 120 ( FIG. 9: Step S202). The superheat degree calculation unit 190a calculates the first superheat degree SHh at the gas outlet of the HIC heat exchanger 50 by subtracting the HIC inlet temperature Thi from the HIC outlet temperature Tho (FIG. 9: Step S203).

  The superheat degree determination unit 190b compares the first superheat degree SHh calculated by the superheat degree calculation unit 190a with the fourth set value, and determines whether or not the first superheat degree SHh is less than the fourth set value. (FIG. 9: Step S204). When the superheat degree determination unit 190b determines that the first superheat degree SHh is less than the fourth set value (FIG. 9: Step S204 / Yes), the valve control unit 190c determines the opening degree of the sub expansion valve 40. The heat exchange amount of the HIC heat exchanger 50 is suppressed by reducing the size (FIG. 9: Step S205).

  On the other hand, when it is determined that the first superheat degree SHh is equal to or greater than the fourth set value (FIG. 9: Step S204 / No), the superheat degree determination unit 190b compares the first superheat degree SHh with the fifth set value. Then, it is determined whether or not the first superheat degree SHh is larger than the fifth set value (FIG. 9: Step S206). When the superheat degree determination unit 190b determines that the first superheat degree SHh is larger than the fifth set value (FIG. 9: Step S206 / Yes), the valve control unit 190c increases the opening degree of the sub expansion valve 40. Then, the heat exchange amount of the HIC heat exchanger 50 is increased (FIG. 9: Step S207). On the other hand, when the superheat degree determination unit 190b determines that the first superheat degree SHh is equal to or less than the fifth set value (FIG. 9: Step S206 / No), the valve control unit 190c presents the current sub-expansion valve. The opening degree of 40 is maintained (FIG. 9: Step S208). That is, the valve control unit 190c controls the opening degree of the sub-expansion valve 40 so that the first degree of superheat falls within a target range that is not less than the fourth set value and not more than the fifth set value.

  Next, the superheat degree calculation unit 190a inputs the suction pressure Ps detected by the pressure sensor 110 (FIG. 9: Step S209), and inputs the suction temperature Ts detected by the suction temperature sensor 230 (FIG. 9: Step). S210). The superheat degree calculation unit 190a calculates the saturation temperature f (Ps) of the suction pressure Ps, and subtracts the saturation temperature f (Ps) from the suction temperature Ts to calculate the third superheat degree SHs of the suction port of the compressor 15. (FIG. 9: Step S211).

  The superheat degree determination unit 190b compares the third superheat degree SHs calculated by the superheat degree calculation unit 190a with the sixth set value, and determines whether the third superheat degree SHs is less than the sixth set value. (FIG. 9: Step S212). When the superheat degree determination unit 190b determines that the third superheat degree SHs is less than the sixth set value (FIG. 9: Step S212 / Yes), the valve control unit 190c determines the opening degree of the main expansion valve 80. The heat exchange amount of the evaporator 60 is suppressed by reducing the size (FIG. 9: Step S213). On the other hand, when the superheat determination unit 190b determines that the third superheat degree SHs is equal to or greater than the sixth set value (FIG. 9: step S212 / No), the valve control unit 190c opens the main expansion valve 80. The degree is increased, and the heat exchange amount of the evaporator 60 is increased (FIG. 9: Step S214).

  FIG. 10 is a characteristic diagram showing the result of simulating the relationship between the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity of the refrigeration cycle apparatus 200 and COP. With reference to FIG. 10, the area | region where COP of the refrigerating-cycle apparatus 200 takes a favorable value is demonstrated. As shown in FIG. 10, the COP in the refrigeration cycle apparatus 200 has a peak value in the vicinity where the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is 5.5%. That is, if the length of the heat transfer section of the internal heat exchanger 70 is too short, the suction superheat degree of the compressor 10 becomes small and the increase in the discharge temperature of the compressor 10 becomes small, so that the COP becomes low. On the other hand, if the length of the heat transfer section of the internal heat exchanger 70 is too long, the refrigerant pressure loss on the low-pressure gas side of the internal heat exchanger 70 increases and COP decreases.

  As shown in FIG. 10, the refrigeration cycle apparatus 200 is operated in a region where the COP takes a good value if the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is less than 7%. Can do. Also in the second embodiment, the region where COP takes a good value is a region where COP is 100% or more. That is, in the refrigeration cycle apparatus 200, the length of the heat transfer portion of the internal heat exchanger 70 is set so that the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity is less than 7%.

  FIG. 11 is a characteristic diagram showing the relationship between the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity of the refrigeration cycle apparatus 200 and the first superheat degree SHh at the outlet of the HIC heat exchanger 50. With reference to FIG. 11, the adjustment method of the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity will be described. As shown in FIG. 11, by controlling the first superheat degree SHh at the outlet of the HIC heat exchanger 50, the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity can be controlled. In the second embodiment, in order to set the ratio of the heat exchange amount of the internal heat exchanger 70 to the total refrigeration capacity to be less than 7%, the valve control unit 190c has a first superheat degree SHh of 15 ° C. or less, which is the target range. The degree of opening of the sub expansion valve 40 is controlled so as to be in the range.

  FIG. 12 is a characteristic diagram showing the relationship between the COP and the ratio of the heat exchange amount of the HIC heat exchanger 50 to the heat exchange amount of the internal heat exchanger 70 in the refrigeration cycle apparatus 200. With reference to FIG. 12, the relationship between the heat exchange amount of the HIC heat exchanger 50 and the internal heat exchanger 70 and the region where the COP of the refrigeration cycle apparatus 200 takes a good value will be described.

  Regarding the refrigerant flow during the heating operation, since the HIC heat exchanger 50 is on the upstream side and the internal heat exchanger 70 is on the downstream side, if the heat exchange amount of the HIC heat exchanger 50 is increased, the internal heat exchanger 50 The temperature of the high-pressure liquid refrigerant flowing into 70 decreases. That is, as the heat exchange amount of the HIC heat exchanger 50 increases, the heat exchange amount of the internal heat exchanger 70 decreases, and as shown in FIG. 12, the HIC heat with respect to the heat exchange amount of the internal heat exchanger 70 There is a peak value of COP with respect to the ratio of the heat exchange amount of the exchanger 50.

  In the second embodiment, the ratio of the heat exchange amount of the HIC heat exchanger 50 to the heat exchange amount of the internal heat exchanger 70 is set to be 125% or more and 280% or less. With this setting, the refrigeration cycle apparatus 200 can be operated in a region where the COP takes a good value as shown in FIG.

  As described above, the refrigeration cycle apparatus 200 according to the second embodiment has the HIC heat exchanger 50 connected in series to the internal heat exchanger 70, and the HIC heat exchanger 50 is connected to the condenser 30 from the main unit. A configuration is adopted in which heat is exchanged between the refrigerant flowing in through the pipe 1 and the refrigerant flowing in from the condenser 30 via the sub-expansion valve 40 on the bypass pipe 2. For this reason, since the amount of heat exchange by the internal heat exchanger 70 can be reduced, the length of the heat transfer portion of the internal heat exchanger 70 that causes the refrigerant pressure loss on the suction side of the compressor 10 is more than necessary. The operation in the region where the COP is high can be realized without increasing the length. That is, according to the refrigeration cycle apparatus 200, the amount of heat exchange by the internal heat exchanger 70 can be reduced. Therefore, even when HFO-1234yf or HFO-1234ze is used as the refrigerant, heat transfer of the internal heat exchanger 70 is achieved. The length of the part can be shortened and the efficiency can be improved. In addition, the valve control unit 190c employs a configuration in which the opening degree of the main expansion valve 80 is controlled so that the third superheat degree becomes a preset target value (sixth set value). The influence of the control of the valve 40 on the evaporator 60 side can be minimized.

  Further, in the refrigeration cycle apparatus 200, since the length of the heat transfer section of the internal heat exchanger 70 can be shortened, productivity can be improved. Furthermore, since the bypass pipe 2 passing through the HIC heat exchanger 50 is configured to flow a small amount of two-phase refrigerant, the HIC heat exchanger 50 is configured with a pipe that is thinner than the internal heat exchanger 70. Can be made compact. In addition, by reducing the size of the HIC heat exchanger 50 by using a thin pipe, the size of the device can be made smaller than that of the conventional configuration, thereby improving the installation property, reducing the weight of the device, and reducing the cost. Can be realized. In addition, since the refrigeration cycle apparatus 100 according to the second embodiment is configured to use HFO-1234yf or HFO-1234ze having a low global warming potential, the influence on the global environment can be reduced. .

  Each embodiment mentioned above is a suitable example in a refrigerating cycle device, and the technical scope of the present invention is not limited to these modes. For example, in Embodiments 1 and 2 described above, a mixed refrigerant containing HFO-1234yf or HFO-1234ze is exemplified as the refrigerant used by the refrigeration cycle apparatuses 100 and 200, but the refrigerant is not limited to this, for example, HFO A single refrigerant of −1234yf or HFO-1234ze may be used. Further, as the mixed refrigerant containing HFO-1234yf or HFO-1234ze, a mixed refrigerant obtained by mixing HFO-1234yf or HFO-1234ze and R32 may be used. Moreover, the detection result used for the calculation of the first superheat degree is not limited to that by each sensor illustrated in each embodiment, and for example, the calculation method in the first embodiment may be adopted in the second embodiment. The calculation method in the second embodiment may be adopted in the first embodiment. Furthermore, the control device 90 according to the first embodiment may perform the determination process using the third superheat degree, and the control device 190 according to the second embodiment may perform the determination process using the second superheat degree. May be performed.

  1 Main piping, 2 Bypass piping, 10, 15 Compressor, 20 Four-way valve, 30 Condenser, 40 Secondary expansion valve, 50 HIC heat exchanger, 60 Evaporator, 70 Internal heat exchanger, 80 Main expansion valve, 90, 190 control device, 90a, 190a superheat degree calculation unit, 90b, 190b superheat degree determination unit, 90c, 190c valve control unit, 100, 200 refrigeration cycle device, 110 pressure sensor, 120 HIC outlet temperature sensor, 130 evaporator outlet temperature sensor 210 HIC inlet temperature sensor, 230 suction temperature sensor, Ps suction pressure, SHh first superheat degree, She second superheat degree, SHs third superheat degree, The evaporator outlet temperature, Thi HIC inlet temperature, ThO HIC outlet temperature, Ts Inhalation temperature, f (Ps) Saturation temperature.

Claims (10)

A refrigerant circuit in which a compressor, a condenser, a main expansion valve, and an evaporator are connected via a main pipe;
The refrigerant that flows between the condenser and the main expansion valve and the refrigerant that flows between the evaporator and the compressor exchange heat, and the refrigerant that has flowed out of the evaporator flows into the suction side of the compressor An internal heat exchanger to flow into
An HIC heat exchanger provided between the condenser and the internal heat exchanger and connected in series to the internal heat exchanger;
A bypass pipe branched from between the condenser and the HIC heat exchanger, and leading the refrigerant to the compressor via the HIC heat exchanger;
A sub-expansion valve that depressurizes the refrigerant flowing into the bypass pipe from the condenser and flows out to the HIC heat exchanger;
A state detector for detecting the state of the refrigerant flowing through the refrigerant circuit;
A control device for controlling the opening of the sub-expansion valve based on the detection result by the state detection unit,
The HIC heat exchanger exchanges heat between the refrigerant flowing from the condenser through the main pipe and the refrigerant flowing from the condenser via the sub-expansion valve,
The state detection unit
A pressure sensor that detects a suction pressure that is a pressure of a refrigerant sucked into the compressor;
An HIC outlet temperature sensor that detects an HIC outlet temperature that is a temperature of a refrigerant flowing out of the HIC heat exchanger,
The control device includes:
A superheat degree calculation unit that calculates a first superheat degree that is a superheat degree of the outlet of the HIC heat exchanger using a result of detection by the state detection part;
The way the first degree of superheat becomes the preset target range, have a, a valve control unit for controlling the opening of the sub-expansion valve,
The superheat degree calculation unit calculates a saturation temperature from the suction pressure detected by the pressure sensor, and subtracts the saturation temperature from the HIC outlet temperature detected by the HIC outlet temperature sensor. A refrigeration cycle device that calculates the degree of superheat . The state detection unit
Having an evaporator outlet temperature sensor for detecting the evaporator outlet temperature is the temperature of the refrigerant flowing out of the pre-Symbol evaporator,
The superheat degree calculation unit has a function of calculating a second superheat degree that is a superheat degree of the outlet of the evaporator based on a detection result by the pressure sensor and the evaporator outlet temperature sensor,
The valve control unit
While having a function of controlling the opening of the main expansion valve,
Wherein such second degree of superheat becomes the preset target value, the refrigeration cycle apparatus according to claim 1 for controlling the opening of the main expansion valve. The state detection unit
Includes a suction temperature sensor for detecting the intake temperature is the temperature of the gas refrigerant sucked into the compressor flows before SL internal heat exchanger, a,
The superheat degree calculation unit has a function of calculating a third superheat degree that is a superheat degree of the suction port of the compressor based on a detection result by the pressure sensor and the suction temperature sensor,
The valve control unit
While having a function of controlling the opening of the main expansion valve,
The third degree of superheat so that a preset target value, the refrigeration cycle apparatus according to claim 1 for controlling the opening of the main expansion valve. The refrigeration cycle apparatus according to any one of claims 1 to 3 , wherein the target range is set so that a ratio of a heat exchange amount of the internal heat exchanger to a total refrigeration capacity is less than 7%. The refrigeration cycle apparatus according to claim 4 , wherein the target range is set so that a ratio of a heat exchange amount of the internal heat exchanger to a total refrigeration capacity is 2.4% or more. The refrigeration cycle apparatus according to any one of claims 1 to 5 , wherein the bypass pipe is connected to the main pipe extending from an outlet of the internal heat exchanger. The refrigeration cycle apparatus according to any one of claims 1 to 5 , wherein the compressor includes an injection port that injects a refrigerant that flows into the bypass pipe and flows out of the HIC heat exchanger. The refrigeration cycle apparatus according to claim 6 , wherein a ratio of a heat exchange amount of the HIC heat exchanger to a heat exchange amount of the internal heat exchanger is set to be 160% or more and 700% or less. The refrigeration cycle apparatus according to claim 7 , wherein a ratio of a heat exchange amount of the HIC heat exchanger to a heat exchange amount of the internal heat exchanger is set to be 125% or more and 280% or less. 10. The refrigerant according to any one of claims 1 to 9 , wherein a single refrigerant of HFO-1234yf or HFO-1234ze or a mixed refrigerant containing HFO-1234yf or HFO-1234ze is used as a refrigerant circulating through the main pipe and the bypass pipe. Refrigeration cycle equipment.

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