JP2008241192A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle device capable of cooling a high pressure liquid refrigerant in front of an expansion valve to a temperature not higher than the temperature of a low temperature two-phase refrigerant reduced to an intermediate pressure. <P>SOLUTION: A first sub-cooler 13 and a second sub-cooler 15 are provided between an air side heat exchanger 12 and a first expansion valve 18. The high pressure liquid refrigerant in front of the first expansion valve 18 cooled by the low temperature two-phase refrigerant reduced to the intermediate pressure by the first sub-cooler 13 can thereby be cooled by the low temperature two-phase refrigerant further reduced to low pressure by the second sub-cooler 18. Consequently, the high pressure liquid refrigerant in front of the first expansion valve 18 can be cooled to the temperature not higher than the temperature of the low temperature two-phase refrigerant reduced to the intermediate pressure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus, and more particularly to improving the efficiency of a refrigeration cycle.

  As a conventional refrigeration cycle apparatus, for example, “the refrigerant discharged from the second compressor (12) passes through the four-way switching valve (13) and flows into the heat source side heat exchanger (14), Heat exchange is performed in the counterflow state to condense and become a high-pressure liquid refrigerant (point 5 in Fig. 2) The high-pressure liquid refrigerant flowing out of the heat source side heat exchanger (14) is the first expansion valve. The pressure is reduced at (15) and becomes a two-phase refrigerant (point 4 ′ in FIG. 2) at an intermediate pressure and flows into the gas-liquid separator (16). 2 is separated into a gas refrigerant (point 3 ′ in FIG. 2) and a liquid refrigerant (point 5 ′ in FIG. 2), and the gas refrigerant is sucked into the second compressor (12) through the gas pipe (19). The liquid refrigerant is depressurized by the second expansion valve (17) to become a low-pressure two-phase refrigerant (point 6 in Fig. 2), which is used in the utilization side heat exchanger (18) as a predetermined heat medium. Heat exchange in counterflow Evaporated, the gas refrigerant of low pressure (point of FIG. 1). "Has been proposed as that (for example, see Patent Document 1).

JP 2000-161805 (paragraph numbers 0029 to 0031, FIGS. 1 and 2)

In recent years, refrigerant circuits aimed at improving the efficiency of the refrigeration cycle have been used. In particular, in view of environmental problems, many refrigerant circuits that actively utilize the characteristics of non-azeotropic refrigerants are also used. As a method for improving the efficiency of a refrigeration cycle using a non-azeotropic refrigerant, there is a method for improving the heat exchange efficiency of an evaporator (see, for example, Patent Document 1).
In order to improve the heat exchange efficiency of the evaporator, it is necessary to make the low-temperature low-pressure two-phase refrigerant at the inlet of the evaporator as close to liquid as possible. For this purpose, it is necessary to reduce the temperature of the high-pressure liquid refrigerant before being reduced by the expansion valve as much as possible. In the conventional method, the high-pressure liquid refrigerant before the expansion valve is cooled with a low-temperature two-phase refrigerant reduced to an intermediate pressure. Therefore, there is a problem that the high-pressure liquid refrigerant before the expansion valve cannot be cooled below the temperature of the low-temperature two-phase refrigerant reduced to the intermediate pressure.

  The present invention has been made to solve the above-described problems, and by obtaining a refrigeration cycle apparatus capable of cooling the high-pressure liquid refrigerant before the expansion valve to a temperature equal to or lower than the temperature of the low-temperature two-phase refrigerant reduced to an intermediate pressure. is there.

  In the refrigeration cycle apparatus according to the present invention, in the refrigeration cycle apparatus in which a compressor, a condenser, a first decompression device, and an evaporator are sequentially connected, a part of the refrigerant between the condenser and the first decompression device is provided. A first sub refrigerant circuit that bypasses and merges with the refrigerant between the condenser and the compression chamber in the compressor; a second decompression device provided in the first sub refrigerant circuit; A first subcooler for exchanging heat between the refrigerant decompressed by the second decompression device and the refrigerant between the condenser and the first decompression device; the first subcooler and the first decompression device; A second sub-refrigerant circuit that partially bypasses the refrigerant between the two and joins the refrigerant between the evaporator and the compressor, and a third decompressor provided in the second sub-refrigerant circuit The refrigerant decompressed by the third decompression device, the first subcooler, and the first reduction A refrigerant between the device is obtained and a second sub-cooler for exchanging heat.

  In the present invention, since the first subcooler and the second subcooler are provided between the condenser and the first decompression device, the first subcooler is cooled by the low-temperature two-phase refrigerant decompressed to an intermediate pressure. The high-pressure liquid refrigerant before the first decompression device can be further cooled with the low-temperature two-phase refrigerant decompressed to a low pressure in the second subcooler. Therefore, the high-pressure liquid refrigerant before the first pressure reducing device can be cooled below the temperature of the low-temperature two-phase refrigerant reduced to the intermediate pressure.

Embodiment 1 FIG.
1 is a refrigerant circuit of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. The refrigeration cycle apparatus corresponds to an injection compressor 11 corresponding to the compressor of the present invention, an air side heat exchanger 12 corresponding to the condenser of the present invention, a first subcooler 13, and a second decompression apparatus of the present invention. The second expansion valve 14, the injection circuit 100 corresponding to the first sub refrigerant circuit of the present invention, the second sub cooler 15, the third expansion valve 16 corresponding to the third pressure reducing device of the present invention, and the electromagnetic valve 17 , The second sub refrigerant circuit 101, the first expansion valve 18 corresponding to the first decompression device of the present invention, and the water side heat exchanger 19 corresponding to the evaporator of the present invention. The injection compressor 11 is of a scroll type, for example, and has a structure capable of injecting refrigerant supplied from the injection circuit 100 into the compression chamber via the injection port 11a. The second expansion valve 14 and the first expansion valve 18 are electronic expansion valves capable of variably controlling the opening, for example. The third expansion valve 16 is, for example, a temperature type expansion valve, and the temperature of the low-pressure gas refrigerant that has exited the water-side heat exchanger 19 is detected by the temperature sensing unit 16a, and the opening degree of the valve is controlled according to this detected temperature. Is done. The air-side heat exchanger 12 is, for example, a fin tube heat exchanger that exchanges heat with the outside air blown by a blower or the like. The water-side heat exchanger is, for example, a double-pipe type heat exchanger that exchanges heat in a counter-flow state with a thermal refrigerant (for example, water) used for cooling a predetermined cooling area (for example, indoors or inside a train vehicle). It is an exchanger. As the refrigerant of the refrigeration cycle apparatus, for example, a non-azeotropic refrigerant mixture such as R407C is used. A pseudo-azeotropic refrigerant mixture such as R410A or a single refrigerant such as R22 can also be used.

  Further, the refrigeration cycle apparatus is provided with a control device 401, a compressor capacity detection means 402, and a temperature sensor 403. The temperature sensor 403 measures the outside air temperature T around the refrigeration cycle apparatus. The compressor capacity detection unit 402 measures the capacity Q of the injection compressor 11. The control device 401 stores information such as the outside air temperature T measured by the temperature sensor 403, the capacity Q of the injection compressor 11 measured by the compressor capacity detection means 402, the set temperature T0, and the set capacity Q0 of the injection compressor 11. It has a storage means. Control for controlling the rotation speed of the injection compressor 11, the opening degrees of the second expansion valve 14 and the first expansion valve 18, the opening and closing of the electromagnetic valve 17 and the like based on the information stored in the storage means. Have means. This storage means may be provided outside the control device 401.

First, the refrigeration cycle operation in the refrigeration cycle apparatus of the first embodiment will be described.
FIG. 2 is an example of a Ph diagram illustrating the refrigeration cycle operation in the refrigeration cycle apparatus of the first embodiment. The horizontal axis represents specific enthalpy [kJ / kg], and the vertical axis represents refrigerant pressure [MPa]. The refrigeration cycle operation will be described below with reference to FIG. 1 and FIG.

  The high-temperature and high-pressure gas refrigerant (state 1) discharged from the injection compressor 11 flows into the air-side heat exchanger 12. Thereafter, the air-side heat exchanger 12 is condensed and liquefied while dissipating heat to the outside air to become a high-pressure liquid refrigerant (state 2). The high-pressure liquid refrigerant that has exited the air-side heat exchanger 12 flows into the first subcooler 13. The high-pressure liquid refrigerant (state 2) is cooled by the first subcooler 13 by branching to the injection circuit 100 and reducing the intermediate pressure by the second expansion valve 14 to a low temperature refrigerant (state 3). . A part of the high-pressure liquid refrigerant that has exited the first subcooler 13 is branched into the injection circuit 100, and the main flow flows into the second subcooler 15. The high-pressure liquid refrigerant (state 3) is cooled by the second sub-cooler 15 by branching to the second sub-refrigerant circuit 101, reducing the pressure to a low pressure by the third expansion valve 16 and reducing the temperature to a low temperature ( State 4). A part of the high-pressure liquid refrigerant that has exited the second subcooler 15 is branched into the second sub-refrigerant circuit 101, and the main flow flows into the first expansion valve 18. The high-pressure liquid refrigerant (state 4) is depressurized by the first expansion valve 18, enters a low-pressure two-phase state (state 5), and flows into the water-side heat exchanger 19. In the water-side heat exchanger 19, one of the double pipes of the water-side heat exchanger 19 absorbs heat from a thermal refrigerant (for example, water) that flows opposite to the refrigerant flow direction and evaporates into a low-pressure gas refrigerant (state) 6). Thereafter, it merges with the low-pressure gas refrigerant (state 11) of the second sub refrigerant circuit 101 (state 12) and is sucked into the injection compressor 11.

  On the other hand, the refrigerant branched to the injection circuit 100 (state 3) is reduced to an intermediate pressure by the second expansion valve 14 to become a low-temperature two-phase refrigerant (state 7), flows into the first subcooler 13 and flows into the main stream. To increase the specific enthalpy (state 8). Thereafter, it is injected into the injection compressor 11 via the injection port 11a. In the injection compressor 11, in the process of sucking and increasing the pressure of the low-pressure gas refrigerant (state 12), the refrigerant (state 8) injected from the injection circuit 100 is sucked and joined (state 9). Thereafter, the pressure is increased to a high pressure and discharged (state 1).

  The refrigerant branched to the second sub refrigerant circuit 101 (state 4) is decompressed to a low pressure by the third expansion valve 16 to become a low-temperature two-phase refrigerant (state 10), and flows into the second subcooler 15. Then, it is heated by the mainstream high-pressure liquid refrigerant to increase the specific enthalpy (state 11). After that, the low-pressure gas refrigerant (state 6) exiting the water-side heat exchanger 19 is joined via the second sub refrigerant circuit 101 (state 6) and sucked into the injection compressor 11.

  In the first embodiment, the pressure of the refrigerant decompressed by the third expansion valve 16 (state 10) is smaller than the pressure of the refrigerant decompressed by the first expansion valve 18 (state 5). This is just an example. These pressures are related to the capacity of the injection compressor 11, the opening of the third expansion valve 16, the outside air temperature around the refrigeration cycle device, the temperature of the cooling region (for example, indoors or inside a train vehicle), Or it changes according to conditions, such as the desired temperature of the cooling area | region which a user desires.

  The amount of refrigerant flowing between the air-side heat exchanger 12 and the first expansion valve 18 varies depending on the operating conditions of the refrigeration cycle apparatus. For example, when the temperature in the cooling area (for example, indoors or in a train vehicle) is low or the desired temperature in the cooling area is high, heat exchange between the heat medium (for example, water) and the air in the cooling area is small. Therefore, the temperature of the heat medium flowing into the water-side heat exchanger 19 for heat exchange with the refrigerant remains low. At this time, since the heat exchange between the refrigerant and the heat medium in the water-side heat exchanger 19 is small, the capacity of the injection compressor 11 is reduced. Therefore, the amount of refrigerant flowing between the air side heat exchanger 12 and the first expansion valve 18 is reduced. For example, when the outside air temperature T around the refrigeration cycle apparatus is low, the degree of supercooling of the refrigerant that exchanges heat with the outside air in the air-side heat exchanger 12 increases. Therefore, since the refrigerant refrigerating capacity is increased, the capacity of the injection compressor 11 is reduced. Therefore, the amount of refrigerant flowing between the air side heat exchanger 12 and the first expansion valve 18 is reduced.

  When the amount of refrigerant flowing between the air-side heat exchanger 12 and the first expansion valve 18 decreases, the amount of refrigerant flowing through the second sub refrigerant circuit 101 also decreases, and the third expansion valve 16 is operated. The necessary amount of refrigerant cannot be obtained. Further, the amount of refrigerant flowing in the water-side heat exchanger 19 is also reduced, and the operation of the refrigeration cycle apparatus may become unstable. When the amount of refrigerant necessary for operating the third expansion valve 16 cannot be obtained, the solenoid valve 17 is closed to block the flow of the refrigerant into the second sub refrigerant circuit 101, and all the refrigerant is removed from the water side. By flowing through the heat exchanger 19, the operation of the refrigeration cycle apparatus can be stabilized.

  FIG. 3 is a control flowchart of the solenoid valve 17 in the first embodiment. The storage means of the control device 401 stores a preset temperature T0 and a preset capacity Q0 of the injection compressor 11 in advance. When the capacity Q of the injection compressor 11 measured by the compressor capacity detecting means 402 is equal to or less than the set capacity Q0 or the outside air temperature T measured by the temperature sensor 403 is equal to or less than the set temperature T0, the third expansion valve 16 The control device 401 controls opening and closing of the electromagnetic valve 17 by determining that the amount of refrigerant necessary for operating the refrigerant does not flow into the second sub refrigerant circuit 101.

  In step S201, the capacity Q of the injection compressor 11 is compared with the set capacity Q0. When the capacity Q of the injection compressor 11 is larger than the set capacity Q0, the process proceeds to step S202. When the capacity Q of the injection compressor 11 is smaller than the set capacity Q0, the process proceeds to step S204, where the electromagnetic valve 17 is closed to block the flow of refrigerant into the second sub refrigerant circuit 101. Thereafter, the process returns to step S201. In step S202, the outside air temperature T is compared with the set temperature T0. When the outside air temperature T is higher than the set temperature T0, the process proceeds to step S203, and the electromagnetic valve 17 is opened. Thereafter, the process returns to step S201. When the outside air temperature T is lower than the set temperature T0, the process proceeds to step S204, where the electromagnetic valve 17 is closed to block the flow of refrigerant into the second sub refrigerant circuit 101. Thereafter, the process returns to step S201.

  In the refrigeration cycle apparatus configured as described above, the high-pressure liquid refrigerant cooled by the low-temperature two-phase refrigerant reduced to the intermediate pressure in the first subcooler 13 is further reduced to the low-pressure two-phase in the second subcooler 15. It can be cooled with a refrigerant. For this reason, since the low-pressure two-phase refrigerant at the inlet of the water-side heat exchanger 19 decompressed by the first expansion valve 18 becomes closer to liquid, the enthalpy difference in the water-side heat exchanger 19 (between states 5-6) Can be made larger. Therefore, the heat exchange efficiency of the water side heat exchanger 19, that is, the efficiency of the refrigeration cycle apparatus can be further improved.

  When the amount of refrigerant flowing between the air-side heat exchanger 12 and the first expansion valve 18 is small, the solenoid valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101, and all Since the refrigerant is passed through the water-side heat exchanger 19, the operation of the refrigeration cycle apparatus can be stabilized.

  In the first embodiment, the cooling operation when the water-side heat exchanger 19 serves as an evaporator has been described. However, even during the heating operation in which the arrangement of the air-side heat exchanger 12 and the water-side heat exchanger 19 is changed. Similar effects can be obtained. That is, the high-pressure liquid refrigerant cooled by the low-temperature two-phase refrigerant reduced to the intermediate pressure in the first subcooler 13 can be further cooled by the low-temperature two-phase refrigerant reduced to the low pressure in the second subcooler 15. The low-pressure two-phase refrigerant at the inlet of the air-side heat exchanger 12 decompressed by the one expansion valve 18 becomes closer to a liquid state, and the enthalpy difference in the air-side heat exchanger 12 can be increased. For this reason, the heat absorption capacity of the air-side heat exchanger 12 is improved, and the efficiency of the refrigeration cycle apparatus can be improved.

  When the amount of refrigerant flowing between the water-side heat exchanger 19 and the first expansion valve 18 is small, the solenoid valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101, and all Since the refrigerant is passed through the air-side heat exchanger 12, the operation of the refrigeration cycle apparatus can be stabilized.

Embodiment 2. FIG.
In the first embodiment, the refrigeration cycle apparatus that performs the cooling operation (or heating operation) has been described. However, by providing the refrigerant circuit of the first embodiment with the four-way valve and the check valve, the cooling / heating operation that takes advantage of the effects of the present invention. A possible refrigeration cycle apparatus can be provided. In the second embodiment, items not particularly described are the same as those in the first embodiment, and the same functions are described using the same reference numerals.

  FIG. 4 is a refrigerant circuit of the refrigeration cycle apparatus in Embodiment 2 of the present invention. A four-way valve 20, a check valve unit 21, and a check valve unit 22 are provided for the refrigerant circuit of the first embodiment. The four-way valve 20 is provided on the refrigerant discharge side of the injection compressor 11. The check valve unit 21 allows the refrigerant flow from the air side heat exchanger 12 to the first subcooler 13 and allows the refrigerant flow from the water side heat exchanger 19 to the first subcooler 13. It consists of a check valve 21b. The check valve unit 22 includes a check valve 22a that allows a refrigerant flow from the first expansion valve 18 to the water-side heat exchanger 19 and a refrigerant from the first expansion valve 18 to the air-side heat exchanger 12. It consists of a check valve 22b that allows flow.

  First, the refrigeration cycle operation during the cooling operation in the refrigeration cycle apparatus of the second embodiment will be described with reference to FIGS. 4 and 2. During the cooling operation, the refrigerant flow path of the four-way valve 20 is in the direction of the solid line in FIG. The high-temperature and high-pressure gas refrigerant (state 1) discharged from the injection compressor 11 flows into the air-side heat exchanger 12 through the four-way valve 20. Thereafter, the air-side heat exchanger 12 is condensed and liquefied while dissipating heat to the outside air to become a high-pressure liquid refrigerant (state 2). The high-pressure liquid refrigerant that has exited the air-side heat exchanger 12 flows into the first subcooler 13 through the check valve 21a. The high-pressure liquid refrigerant (state 2) is cooled by the first subcooler 13 by branching to the injection circuit 100 and reducing the intermediate pressure by the second expansion valve 14 to a low temperature refrigerant (state 3). . A part of the high-pressure liquid refrigerant that has exited the first subcooler 13 is branched into the injection circuit 100, and the main flow flows into the second subcooler 15. The high-pressure liquid refrigerant (state 3) is cooled by the second sub-cooler 15 by branching to the second sub-refrigerant circuit 101, reducing the pressure to a low pressure by the third expansion valve 16 and reducing the temperature to a low temperature ( State 4). A part of the high-pressure liquid refrigerant that has exited the second subcooler 15 is branched into the second sub-refrigerant circuit 101, and the main flow flows into the first expansion valve 18. The high-pressure liquid refrigerant (state 4) is depressurized by the first expansion valve 18, enters a low-pressure two-phase state (state 5), and flows into the water-side heat exchanger 19 through the check valve 22a. In the water-side heat exchanger 19, one of the double pipes in the water-side heat exchanger 19 absorbs heat from a thermal refrigerant (for example, water) that flows opposite to the refrigerant flow direction and evaporates to become a low-pressure gas refrigerant ( State 6). Thereafter, it merges with the low-pressure gas refrigerant (state 11) of the second sub refrigerant circuit 101 (state 12) and is sucked into the injection compressor 11.

  On the other hand, the refrigerant branched to the injection circuit 100 (state 3) is reduced to an intermediate pressure by the second expansion valve 14 to become a low-temperature two-phase refrigerant (state 7), flows into the first subcooler 13 and flows into the main stream. To increase the specific enthalpy (state 8). Thereafter, it is injected into the injection compressor 11 via the injection port 11a. In the injection compressor 11, in the process of sucking and increasing the pressure of the low-pressure gas refrigerant (state 12), the refrigerant (state 8) injected from the injection circuit 100 is sucked and joined (state 9). Thereafter, the pressure is increased to a high pressure and discharged (state 1).

  The refrigerant branched to the second sub refrigerant circuit 101 (state 4) is decompressed to a low pressure by the third expansion valve 16 to become a low-temperature two-phase refrigerant (state 10), and flows into the second subcooler 15. Then, it is heated by the mainstream high-pressure liquid refrigerant to increase the specific enthalpy (state 11). After that, the low-pressure gas refrigerant (state 6) exiting the water-side heat exchanger 19 is joined via the second sub refrigerant circuit 101 (state 6) and sucked into the injection compressor 11.

  Then, the refrigerating cycle operation | movement at the time of the heating operation in the refrigerating cycle apparatus of this Embodiment 2 is demonstrated using FIG.4 and FIG.2. Strictly speaking, the values of the refrigerant pressure [MPa] and the specific enthalpy [kJ / kg] in each state (states 1 to 12) in the Ph diagram during the cooling operation and the Ph diagram during the heating operation. Is different. However, since the Ph diagrams during the cooling operation and the heating operation have substantially the same shape, the refrigeration cycle operation during the heating operation will be described below with reference to FIG. During the heating operation, the refrigerant flow path of the four-way valve 20 is in the direction of the broken line in FIG. The high-temperature and high-pressure gas refrigerant (state 1) discharged from the injection compressor 11 flows into the water-side heat exchanger 19 through the four-way valve 20. In the water-side heat exchanger 19, one of the double pipes in the water-side heat exchanger 19 dissipates heat to a thermal refrigerant (for example, water) that flows opposite to the refrigerant flow direction, condenses and liquefies, and a high-pressure liquid refrigerant (state 2). The high-pressure liquid refrigerant that has exited the water-side heat exchanger 19 flows into the first subcooler 13 through the check valve 21b. The high-pressure liquid refrigerant (state 2) is cooled by the first subcooler 13 by branching to the injection circuit 100 and exchanging heat with the refrigerant having the low pressure reduced to the intermediate pressure by the second expansion valve 14 (state 3). . A part of the high-pressure liquid refrigerant that has exited the first subcooler 13 is branched into the injection circuit 100, and the main flow flows into the second subcooler 15. The high-pressure liquid refrigerant (state 3) is cooled by the second sub-cooler 15 by branching to the second sub-refrigerant circuit 101, reducing the pressure to a low pressure by the third expansion valve 16 and reducing the temperature to a low temperature ( State 4). A part of the high-pressure liquid refrigerant that has exited the second subcooler 15 is branched into the second sub-refrigerant circuit 101, and the main flow flows into the first expansion valve 18. The high-pressure liquid refrigerant (state 4) is depressurized by the first expansion valve 18, enters a low-pressure two-phase state (state 5), and flows into the air-side heat exchanger 12 through the check valve 22b. In the air-side heat exchanger 12, the low-pressure two-phase refrigerant evaporates while absorbing heat from the outside air to become a low-pressure gas refrigerant (state 6). Thereafter, it merges with the low-pressure gas refrigerant (state 11) of the second sub refrigerant circuit 101 (state 12), and is sucked into the injection compressor 11.

  On the other hand, the refrigerant branched to the injection circuit 100 (state 3) is reduced to an intermediate pressure by the second expansion valve 14 to become a low-temperature two-phase refrigerant (state 7), flows into the first subcooler 13 and flows into the main stream. To increase the specific enthalpy (state 8). Thereafter, it is injected into the injection compressor 11 via the injection port 11a. In the injection compressor 11, in the process of sucking and increasing the pressure of the low-pressure gas refrigerant (state 12), the refrigerant (state 8) injected from the injection circuit 100 is sucked and joined (state 9). Thereafter, the pressure is increased to a high pressure and discharged (state 1).

  The refrigerant branched to the second sub refrigerant circuit 101 (state 4) is decompressed to a low pressure by the third expansion valve 16 to become a low-temperature two-phase refrigerant (state 10), and flows into the second subcooler 15. Then, it is heated by the mainstream high-pressure liquid refrigerant to increase the specific enthalpy (state 11). Thereafter, the low-pressure gas refrigerant (state 6) that has exited the air-side heat exchanger 12 via the second sub-refrigerant circuit 101 (state 12) is merged (state 12) and is sucked into the injection compressor 11.

  FIG. 5 is a control flowchart of the electromagnetic valve 17 in the second embodiment. The set temperature and the set capacity of the injection compressor 11 are different between the cooling operation and the heating operation. Therefore, the storage means of the control device 401 stores in advance the set temperature T0 and set capacity Q0 during cooling operation, and the set temperature T1 and set capacity Q1 during heating operation, respectively. During cooling operation, when the capacity Q of the injection compressor 11 measured by the compressor capacity detecting means 402 is equal to or lower than the set capacity Q0, or the outside air temperature T measured by the temperature sensor 403 is equal to or lower than the set temperature T0, The control device 401 controls the opening and closing of the electromagnetic valve 17 by determining that the amount of refrigerant necessary for operating the third expansion valve 16 does not flow into the second sub refrigerant circuit 101. Further, during the heating operation, the capacity Q of the injection compressor 11 measured by the compressor capacity detecting means 402 is not more than the set capacity Q1, or the outside air temperature T measured by the temperature sensor 403 is not more than the set temperature T1. In this case, it is determined that the amount of refrigerant necessary for operating the third expansion valve 16 does not flow into the second sub refrigerant circuit 101, and the control device 401 controls the opening and closing of the electromagnetic valve 17.

  In step S501, it is determined whether the operation is cooling or heating. If it is a cooling operation, the process proceeds to step S502, and if it is a heating operation, the process proceeds to step S506. During the cooling operation, in step S502, the capacity Q of the injection compressor 11 is compared with the set capacity Q0 during the cooling operation. When the capacity Q of the injection compressor 11 is larger than the set capacity Q0 during the cooling operation, the process proceeds to step S503. When the capacity Q of the injection compressor 11 is smaller than the set capacity Q0 during the cooling operation, the process proceeds to step S505, where the electromagnetic valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101. Thereafter, the process returns to step S501. In step S503, the outside air temperature T is compared with the set temperature T0 during the cooling operation. When the outside air temperature T is higher than the set temperature T0 during the cooling operation, the process proceeds to step S504, and the solenoid valve 17 is opened. Thereafter, the process returns to step S501. When the outside air temperature T is lower than the set temperature T0 during the cooling operation, the process proceeds to step S505, where the solenoid valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101. Thereafter, the process returns to step S501.

  During the heating operation, in step S506, the capacity Q of the injection compressor 11 is compared with the set capacity Q1 during the heating operation. When the capacity Q of the injection compressor 11 is larger than the set capacity Q1 during the heating operation, the process proceeds to step S507. When the capacity Q of the injection compressor 11 is smaller than the set capacity Q1 during the heating operation, the process proceeds to step S509, where the electromagnetic valve 17 is closed and the refrigerant flow into the second sub refrigerant circuit 101 is blocked. Thereafter, the process returns to step S501. In step S503, the outside air temperature T is compared with the set temperature T1 during heating operation. When the outside air temperature T is higher than the set temperature T0 during the heating operation, the process proceeds to step S508, and the solenoid valve 17 is opened. Thereafter, the process returns to step S501. When the outside air temperature T is lower than the set temperature T1 during the heating operation, the process proceeds to step S509, where the electromagnetic valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101. Thereafter, the process returns to step S501.

  In the refrigeration cycle apparatus configured as described above, by switching the four-way valve 20, during the cooling operation, the high-pressure liquid refrigerant cooled by the low-temperature two-phase refrigerant reduced to the intermediate pressure in the first subcooler 13 is further The second subcooler 15 can be cooled with a low-temperature two-phase refrigerant decompressed to a low pressure. For this reason, since the low-pressure two-phase refrigerant at the inlet of the water-side heat exchanger 19 decompressed by the first expansion valve 18 becomes closer to liquid, the enthalpy difference in the water-side heat exchanger 19 (between states 5-6) Can be made larger. Therefore, the heat exchange efficiency of the water side heat exchanger 19, that is, the efficiency of the refrigeration cycle apparatus can be further improved.

  When the amount of refrigerant flowing between the air-side heat exchanger 12 and the first expansion valve 18 is small, the solenoid valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101, and all Since the refrigerant is passed through the water-side heat exchanger 19, the operation of the refrigeration cycle apparatus can be stabilized.

  During the heating operation, the high-pressure liquid refrigerant cooled by the low-temperature two-phase refrigerant reduced to the intermediate pressure in the first subcooler 13 may be further cooled by the low-temperature two-phase refrigerant reduced to the low pressure in the second subcooler 15. Therefore, the low-pressure two-phase refrigerant at the inlet of the air-side heat exchanger 12 reduced in pressure by the first expansion valve 18 becomes closer to a liquid state, and the enthalpy difference in the air-side heat exchanger 12 can be increased. For this reason, the heat absorption capacity of the air-side heat exchanger 12 is improved, and the efficiency of the refrigeration cycle apparatus can be improved.

  When the amount of refrigerant flowing between the water-side heat exchanger 19 and the first expansion valve 18 is small, the solenoid valve 17 is closed to block the refrigerant from flowing into the second sub refrigerant circuit 101, and all Since the refrigerant is passed through the air-side heat exchanger 12, the operation of the refrigeration cycle apparatus can be stabilized.

It is a refrigerant circuit figure of the refrigerating cycle device showing Embodiment 1 of this invention. It is an example of the Ph diagram which shows the refrigerating cycle operation | movement of the refrigerating-cycle apparatus which shows Embodiment 1 of this invention. It is a control flowchart of the solenoid valve 17 which shows Embodiment 1 of this invention. It is a refrigerant circuit figure of the refrigerating-cycle apparatus which shows Embodiment 2 of this invention. It is an example of the Ph diagram which shows the refrigerating cycle operation | movement of the refrigerating-cycle apparatus which shows Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Injection compressor, 11a injection port, 12 Air side heat exchanger, 13 1st subcooler, 14 2nd expansion valve, 15 2nd subcooler, 16 3rd expansion valve, 16a Temperature sensing part, 17 Solenoid valve , 18 First expansion valve, 19 Water side heat exchanger, 20 Four-way valve, 21 Check valve unit, 21a, 21b Check valve, 22 Check valve unit, 22a, 22b Check valve, 100 Injection circuit, 101 Second sub refrigerant circuit, 401 controller, 402 compressor capacity detection means, 403 temperature sensor, Q capacity, Q0 set capacity (during cooling operation), Q1 set capacity (during heating operation), T outside air temperature, T0 set temperature (At the time of cooling operation), T1 set temperature (at the time of heating operation).

Claims (3)

In the refrigeration cycle apparatus in which the compressor, the condenser, the first pressure reducing device, and the evaporator are sequentially connected,
A first sub refrigerant circuit that bypasses a part of the refrigerant between the condenser and the first pressure reducing device and joins the refrigerant between the evaporator and the compression chamber in the compressor;
A second decompression device provided in the first sub refrigerant circuit;
A first subcooler for exchanging heat between the refrigerant decompressed by the second decompression device and the refrigerant between the condenser and the first decompression device;
A second sub refrigerant circuit that partially bypasses the refrigerant between the first subcooler and the first pressure reducing device and joins the refrigerant between the evaporator and the compressor;
A third decompression device provided in the second sub refrigerant circuit;
A second subcooler for exchanging heat between the refrigerant decompressed by the third decompressor and the refrigerant between the first subcooler and the first decompressor;
A refrigeration cycle apparatus comprising: The refrigerant decompressed by the third decompression device is
2. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus has a lower pressure than the refrigerant decompressed by the second decompression apparatus.   The refrigeration cycle apparatus according to claim 1 or 2, wherein in the second sub refrigerant circuit, an electromagnetic valve is provided on the upstream side of the refrigerant flow of the third decompression device.

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