JP6223573B2 - Refrigeration air conditioner - Google Patents

Description

  The present invention relates to a refrigeration air conditioner, and more particularly, to dew condensation on a liquid pipe.

  In the conventional refrigeration air conditioner, the cooling operation of the cooling device is controlled by the controller so that the temperature of the liquid piping does not become lower than the ambient temperature. Thereby, it controls so that the cooling capacity can be enhanced while preventing the occurrence of dew condensation in the liquid piping constituting the refrigerant circulation circuit (see, for example, Patent Document 1).

  In addition, some conventional refrigeration and air-conditioning apparatuses increase the cooling capacity by increasing the subcooling of the liquid refrigerant, thereby further saving energy (for example, see Non-Patent Document 1).

Japanese Patent No. 4444220 (Claim 2) Mitsubishi Electric, “Mitsubishi Electric R410A Low Temperature Equipment General Catalog”, January 2014 edition, p. 6

  When the refrigerating and air-conditioning apparatus described in Patent Literature 1 is updated, the existing local piping may be reused. In this case, the existing liquid piping may not be insulated. If only the refrigeration air conditioner is updated and the existing liquid pipe is used without heat insulation, condensation will occur in the liquid pipe when the surface temperature of the liquid pipe falls below the dew point temperature of the outside air. There have been problems such as water droplets generated by the condensation falling into the room, causing the room to become submerged, and causing mold.

  Further, in the refrigeration air conditioner described in Non-Patent Document 1, when the liquid pipe is not thermally insulated, the temperature of the liquid refrigerant is set to the dew point of the outside air around the liquid pipe so that condensation does not occur in the liquid pipe. Can only be lowered to temperature. For this reason, there was a problem that the subcooling of the liquid refrigerant could not be increased and the cooling capacity could not be increased, so that energy saving could not be ensured.

  Furthermore, when the cooling capacity is increased and the subcooling of the liquid refrigerant is increased so as to save energy, the refrigerant temperature at the outlet of the condenser may be lower than the dew point temperature of the outside air around the liquid piping. As a result, the liquid pipe is condensed, and there is a problem that the liquid pipe needs to be heat-insulated.

  The present invention has been made to solve the above-described problems, and a first object is to make the liquid refrigerant condensed by the heat source lower than the outside air dew point temperature lower than the dew point temperature of the surrounding outside air. Even in such a case, the object is to obtain a refrigeration air conditioner that does not cause condensation in the liquid piping.

  According to the second object of the present invention, when heat insulation is applied to local piping, a large construction cost is required and a long construction time is required. For this reason, by adjusting the temperature of the liquid refrigerant, it is possible to select whether or not to heat-insulate the local liquid piping to prevent condensation on one model, and the cost of heat-insulating the customer, etc. Another object is to obtain a refrigeration air conditioner that can flexibly meet demands for delivery and delivery.

The refrigerating and air-conditioning apparatus according to the present invention further includes a main refrigerant circuit in which a compressor, a condenser, a first pressure reducing device, and an evaporator are connected in an annular shape via a refrigerant pipe, and further cools the refrigerant on the outlet side of the condenser A subcooling refrigerant circuit including a heat exchanger, a bypass circuit connected between a refrigerant pipe upstream of the heat exchanger and a refrigerant pipe downstream of the heat exchanger, and bypassing the heat exchanger, The bypass circuit includes a part of the refrigerant condensed in the condenser and bypasses the heat exchanger and sends the refrigerant to a refrigerant pipe on the downstream side of the heat exchanger .

  According to this invention, it was set as the structure which has a bypass circuit which bypasses the means to cool the refrigerant | coolant using the 1st heat source which is less than external air dew point temperature. As a result, even when the refrigerant condensed by the means for cooling the refrigerant using the first heat source that is lower than the outside air dew point temperature becomes equal to or lower than the dew point temperature of the surrounding outside air, the first heat source that is lower than the outside air dew point temperature is used. The temperature of the liquid refrigerant is adjusted to exceed the dew point temperature by adding superheated gas from the compressor to the refrigerant condensed by the means for cooling the refrigerant. By doing in this way, the effect that dew condensation is not produced in refrigerant piping (liquid piping) can be acquired.

It is a figure which shows schematic structure of the refrigerant circuit of the refrigerating air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows schematic structure of the refrigerant circuit of the refrigerating air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows schematic structure of the refrigerant circuit of the refrigerating air conditioning apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows schematic structure of the refrigerant circuit of the refrigerating air conditioning apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows the control action of the flow control apparatus of the bypass circuit of FIG.

Embodiment 1 FIG.
1 is a refrigerant circuit diagram of a refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 1, the refrigerant circuit 100 of the refrigerating and air-conditioning apparatus includes a compressor 1, a means 2 for cooling refrigerant using a first heat source that is lower than an outside air dew point temperature, a use side expansion valve 3, and a use side heat exchange. The vessel 4 is configured to be connected annularly via a refrigerant pipe. A circuit having these configurations is referred to as a main refrigerant circuit.

  The compressor 1 and the means 2 for cooling the refrigerant using the first heat source lower than the outside air dew point temperature constitute a heat source side unit, and the use side expansion valve 3 and the use side heat exchanger 4 constitute a use side unit. doing. The means 2 for cooling the refrigerant using the first heat source lower than the outside air dew point temperature and the use side expansion valve 3 are connected by a liquid pipe 5, and the liquid pipe 5 includes an on-site connection liquid pipe 20. The use side heat exchanger 4 and the compressor 1 are connected by a gas pipe 7, and the gas pipe 7 includes an on-site connection gas pipe 21. The local connection liquid pipe 20 and the local connection gas pipe 21 include cases where existing pipes are used.

  The refrigerant circuit 100 of the refrigeration air conditioner further includes a bypass circuit 11 (sub refrigerant circuit). The bypass circuit 11 is connected between the inlet side refrigerant pipe and the outlet side refrigerant pipe of the means 2 for cooling the refrigerant using the first heat source lower than the outside air dew point temperature. The bypass circuit 11 sends a part of the refrigerant discharged from the compressor 1 to the liquid pipe 5 by bypassing the means 2 for cooling the refrigerant using the first heat source lower than the outside air dew point temperature.

  In the first embodiment, the means 2 for cooling the refrigerant using the first heat source that is lower than the outside air dew point temperature is, for example, the outside air dew point temperature of tap water, ground water, geothermal heat, an evaporator of another refrigeration apparatus, or the like. Heat exchange with lower temperature heat source (first heat source). Thereby, the refrigerant | coolant of the means 2 which cools the refrigerant | coolant using the 1st heat source which is less than an external air dew point temperature is cooled.

Next, the operation of the refrigerating and air-conditioning apparatus according to Embodiment 1 will be described with reference to FIG.
The refrigerant in the refrigerant circuit 100 is compressed into a high-temperature and high-pressure superheated gas in the compressor 1 and then sent to the means 2 for cooling the refrigerant using the first heat source that is lower than the outside air dew point temperature. The refrigerant that passes through the means 2 for cooling the refrigerant using the first heat source that is lower than the outside air dew point temperature is condensed into a high-temperature and high-pressure liquid refrigerant by exchanging heat with the first heat source. The liquid refrigerant passes through the liquid pipe 5 and is passed through the use-side expansion valve 3 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. The low-temperature low-pressure gas-liquid two-phase refrigerant is heat-exchanged with the surrounding air and water in the use-side heat exchanger 4 to become a low-temperature and low-pressure superheated gas state, passes through the gas pipe 7, and again enters the compressor 1. Inhaled. By performing this series of operations, the refrigerant cycle of the main refrigerant circuit is configured.

  The bypass circuit 11 connected to both ends of the means 2 for cooling the refrigerant using the first heat source that is lower than the outside air dew point temperature converts a part of the refrigerant that has become high temperature and high pressure superheated gas in the compressor 1 to the outside air dew point temperature. The second means for cooling the refrigerant using the first heat source that is below the outside air dew point temperature is bypassed by branching upstream of the means 2 for cooling the refrigerant using the first heat source that is less than The cooled refrigerant flowing from the means 2 for cooling the refrigerant using one heat source and the refrigerant using the first heat source below the outside air dew point temperature are merged downstream of the means 2 for cooling and sent to the liquid pipe 5. The flow rate of the refrigerant branched to the bypass circuit 11 is, for example, the flow path resistance (tube diameter, length) of the means 2 for cooling the refrigerant using the first heat source that is lower than the outside air dew point temperature and the flow path of the bypass circuit 11. It is adjusted by the ratio with the resistance (tube diameter, length).

As described above, in the first embodiment, the bypass circuit 11 (sub-refrigerant circuit) is provided in the main refrigerant circuit, and the high-temperature and high-pressure liquid refrigerant and the superheated gas are merged, thereby adjusting the temperature of the liquid refrigerant to the liquid pipe. The ambient temperature around 5 can be higher. Thereby, it is possible to obtain a refrigerating and air-conditioning apparatus in which condensation does not occur in the liquid pipe 5 (particularly the on-site connection liquid pipe 20) regardless of the presence or absence of heat insulation treatment on the liquid pipe 5 (particularly on-site connection liquid pipe 20). .
For this reason, according to the first embodiment, when the surface temperature of the liquid pipe 5 is lower than the dew point temperature of the surrounding outside air, dew condensation occurs on the surface of the liquid pipe 5, and the liquid pipe 5 The conventional problem that condensation water hangs down on the back of the ceiling where the slab is placed, the back of the ceiling and the room become submerged, and mold occurs is eliminated.

  In the first embodiment, the temperature of the liquid refrigerant is set higher than the temperature of the outside air to prevent the condensation on the liquid pipe 5, but the present invention is not limited to this. For example, even if the temperature of the liquid refrigerant is higher than the dew point temperature of the outside air, it is possible to prevent the occurrence of condensation.

  The use side expansion valve 3 corresponds to the “first decompression device” of the present invention, and the use side heat exchanger 4 corresponds to the “evaporator” of the present invention. Further, the liquid pipe 5 corresponds to the “refrigerant pipe between the means for cooling the refrigerant using the first heat source below the outside air dew point temperature and the first pressure reducing device” of the present invention.

Embodiment 2. FIG.
In the second embodiment, a supercooled refrigerant circuit is added to the refrigerant circuit of the first embodiment. In the second embodiment, the basic configuration of the main refrigerant circuit is the same as the configuration of the main refrigerant circuit in the first embodiment. Therefore, the present embodiment will be mainly described below with respect to the differences from the first embodiment. 2 will be described.

As shown in FIG. 2, the refrigerant circuit 100 of the refrigeration air conditioner includes a supercooling refrigerant circuit 30. The subcooling refrigerant circuit 30 is configured such that the expansion device 12, the heat exchanger 13, and the refrigerant pipe 14 are connected in order.
The inlet of the bypass circuit 11 is provided between the outlet side of the condenser 6 and the refrigerant pipe on the upstream side of the heat exchanger 13, and the outlet of the bypass circuit 11 branches from the refrigerant pipe on the downstream side of the heat exchanger 13. It is provided between the unit 16. Thereby, the bypass circuit 11 is configured to bypass the heat exchanger 13.
The supercooling refrigerant circuit 30 is connected to the branch portion 16 downstream of the outlet of the bypass circuit 11, and then connected to the heat exchanger 13 via the expansion device 12. The heat exchanger 13 is provided between the inlet of the bypass circuit 11 and the outlet of the bypass circuit 11, and the refrigerant decompressed by the expansion device 12 (first refrigerant) and before branching on the outlet side of the condenser 6 Heat exchange with the other refrigerant (second refrigerant). The refrigerant heat-exchanged by the heat exchanger 13 is sent out to the injection pipe 1 a of the compressor 1 via the refrigerant pipe 14. The compressor 1 causes the medium-temperature / medium-pressure refrigerant flowing from the injection pipe 1 a to flow into an intermediate portion of the compression stroke of the compressor 1.

Next, the operation of the refrigerating and air-conditioning apparatus according to Embodiment 2 will be described with reference to FIG.
First, the operation of the supercooling refrigerant circuit 30 will be described.
The supercooling refrigerant circuit 30 branches a part of the high-temperature and high-pressure liquid refrigerant that has come out of the condenser 6 at the branching section 16 and causes the refrigerant to flow through the expansion device 12. The expansion device 12 is a variable flow rate adjusting valve that controls the flow rate, and causes the high-temperature and high-pressure liquid refrigerant to flow through the heat exchanger 13 as a medium-temperature and medium-pressure gas-liquid two-phase refrigerant (second heat source). The heat exchanger 13 exchanges heat between the high-temperature and high-pressure liquid refrigerant that has flowed out of the condenser 6 and the medium-temperature and medium-pressure gas-liquid refrigerant (second heat source) that flows in the supercooled refrigerant circuit 30. Subcooling is added to the liquid refrigerant on the outlet side 6. Thereafter, the refrigerant flowing through the supercooled refrigerant circuit 30 flows into the refrigerant pipe 14.

  The refrigerant that has flowed into the refrigerant pipe 14 (medium-temperature medium-pressure refrigerant) flows into an intermediate portion of the compressor 1 through the injection pipe 1a. Thereby, the compressor 1 can be cooled and the discharge refrigerant temperature and the motor temperature of the compressor 1 can be lowered.

Next, the operation of the refrigerating and air-conditioning apparatus according to Embodiment 2 will be described based on the operation of the refrigerant pipe 14 described above.
The refrigerant in the refrigerant circuit 100 is compressed into a high-temperature and high-pressure superheated gas by the compressor 1, is then heat-exchanged with the first heat source in the condenser 6, and is condensed into a high-temperature and high-pressure liquid refrigerant. The liquid refrigerant exiting the condenser 6 is supercooled at a high pressure by the heat exchanger 13 of the supercooling refrigerant circuit 30 as described above.
Further, the bypass circuit 11 branches a part of the refrigerant that has become high-temperature and high-pressure superheated gas in the compressor 1 on the downstream side of the condenser 6 to bypass the heat exchanger 13, and is cooled by flowing from the heat exchanger 13. The refrigerant is combined with the downstream side of the heat exchanger 13 and sent to the liquid pipe 5.
After that, as in the first embodiment, the refrigerant sent to the liquid pipe 5 passes through the use side expansion valve 3 and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. The heat is exchanged with the air and water to form a low-temperature and low-pressure superheated gas state, and is sucked into the compressor 1 again.

As described above, according to the second embodiment, the high-temperature and high-pressure liquid refrigerant that has passed through the condenser 6 is largely supercooled by the heat exchanger 13 of the supercooling refrigerant circuit 30. Even when the temperature of the liquid refrigerant is equal to or lower than the temperature of the outside air, the temperature of the liquid refrigerant is made higher than the temperature of the outside air around the liquid pipe 5 by joining the high-temperature and high-pressure liquid refrigerant by the bypass circuit 11. Can be high. Thereby, it is possible to obtain a refrigerating and air-conditioning apparatus in which condensation does not occur in the liquid pipe 5 (particularly the on-site connection liquid pipe 20) regardless of the presence or absence of heat insulation treatment on the liquid pipe 5 (particularly on-site connection liquid pipe 20). .
Further, since the refrigerant in the supercooling refrigerant circuit 30 is returned to the compressor 1, the medium temperature and the intermediate pressure are set by the expansion device 12 of the supercooling refrigerant circuit 30, and the refrigerant in the main refrigerant circuit is changed by the heat exchanger 13. The heat-exchanged refrigerant can be put into the compressor 1 and the compressor 1 can be cooled.

  The expansion device 12 corresponds to the “second decompression device” of the present invention. The refrigerant on the downstream side of the expansion device 12 of the subcooling refrigerant circuit 30 (medium temperature / medium pressure refrigerant) corresponds to the “first refrigerant” of the present invention, and the refrigerant on the outlet side of the condenser 6 (high temperature / high pressure liquid refrigerant). ) Corresponds to the “second refrigerant” in the present invention. The liquid pipe 5 corresponds to the “refrigerant pipe between the condenser and the first pressure reducing device” of the present invention.

Embodiment 3 FIG.
In the third embodiment, a variable flow rate adjusting valve or a switching valve that can be opened and closed is added to the bypass circuit 11 of the second embodiment. In the third embodiment, the basic configuration of the refrigerant circuit 100 is the same as the configuration of the refrigerant circuit 100 in the second embodiment. Therefore, the present embodiment will be mainly described below with respect to the differences from the second embodiment. 3 will be described.

  As shown in FIG. 3, the refrigerant circuit 100 of the refrigeration air conditioner further includes a valve 15 in the bypass circuit 11 that bypasses the heat exchanger 13. The valve 15 of the bypass circuit 11 is a variable flow rate adjusting valve that controls the flow rate of the refrigerant, or a switching valve that can open and close the flow path of the refrigerant.

Next, the operation of the valve 15 of the bypass circuit 11 will be described with reference to FIG.
When the temperature of the liquid refrigerant in the liquid pipe 5 exceeds the ambient outside air temperature, the liquid pipe 5 does not condense, so the valve 15 of the bypass circuit 11 is closed.
However, when the temperature of the liquid refrigerant in the liquid pipe 5 is equal to or lower than the ambient outside air temperature, the valve 15 of the bypass circuit 11 is opened to allow the high-temperature and high-pressure liquid refrigerant to flow to the bypass circuit 11. Thereby, the temperature of the liquid refrigerant is raised so as to exceed the ambient temperature of the surroundings, and condensation of the liquid pipe 5 is prevented.

  In addition, when a variable flow rate adjusting valve that controls the flow rate of the refrigerant is used, the flow rate of the refrigerant flowing through the bypass circuit 11 can be finely adjusted. The temperature is higher than the ambient temperature (or dew point temperature) and can be controlled in the vicinity of that temperature.

  Further, when the switching valve that can be opened and closed is fully closed or the variable flow rate adjustment valve that controls the flow rate of the refrigerant is controlled to be fully closed, the refrigerant does not pass through the bypass circuit 11. Thereby, it can be set as the structure similar to the refrigerant circuit 100 which does not install the bypass circuit 11. FIG.

  As described above, the refrigerating and air-conditioning apparatus according to the third embodiment adjusts the flow rate of the refrigerant with the valve 15 of the bypass circuit 11 and condenses with the condenser 6 when the local liquid piping 5 cannot be insulated. The liquid refrigerant that has been supercooled by the heat exchanger 13 is merged with the liquid refrigerant that has been added. Thereby, the temperature of the liquid refrigerant can be made higher than the outside air temperature around the liquid pipe 5, and condensation can be prevented from occurring in the liquid pipe 5.

  On the other hand, when the local liquid pipe 5 (particularly, the local connection liquid pipe 20) can be insulated (or when the existing refrigerant pipe subjected to the heat insulation is used as the local connection liquid pipe 20), the valve 15 of the bypass circuit 11 is used. Is fully closed, and all of the high-temperature and high-pressure liquid refrigerant discharged from the condenser 6 is supercooled by the heat exchanger 13, so that the liquid refrigerant can be largely subcooled. Thereby, the cooling capacity of the refrigeration air conditioner is increased, and energy saving can be ensured.

  From these facts, it is possible to flexibly meet the customer's cost of heat treatment and delivery requirements by selecting whether or not heat treatment to prevent condensation on the local liquid piping 5 with one model. A refrigeration air conditioner that can be used can be obtained.

Embodiment 4 FIG.
In the fourth embodiment, the opening degree of the valve 15 of the bypass circuit 11 of the third embodiment is automatically controlled. Since the configuration of the refrigerant circuit 100 of the fourth embodiment is the same as the configuration of the third embodiment, the fourth embodiment will be described below with a focus on differences from the third embodiment.

  As shown in FIG. 4, the refrigerant circuit 100 of the fourth embodiment further includes an outside air temperature sensor 31, a refrigerant temperature sensor 32, and a flow rate control device 33. The flow control device 33 is configured by, for example, a microcomputer.

  The outside air temperature sensor 31 detects the surrounding outside air temperature, and the flow control device 33 takes in the outside air temperature data from the outside air temperature sensor 31. Similarly, the refrigerant temperature sensor 32 detects the temperature of the liquid refrigerant flowing through the liquid pipe 5, and the flow rate control device 33 takes in the temperature data of the liquid refrigerant from the refrigerant temperature sensor 32.

  In the flow rate control device 33, for example, the opening degree of the valve 15 of the bypass circuit 11 corresponding to the outside air temperature and the liquid refrigerant temperature is stored in advance in the table, and based on the data of the taken outside air temperature and liquid refrigerant temperature With reference to the table, the opening degree of the valve 15 of the bypass circuit 11 is obtained, and the valve 15 is controlled based on the opening degree.

FIG. 5 is a flowchart showing the control operation of the flow control device 33. Hereinafter, the control operation of the flow control device 33 will be described with reference to FIG. 4 based on the steps of FIG.
(S1)
Start the refrigeration air conditioner.
(S2)
The flow rate control device 33 of the bypass circuit 11 takes in information on the outside air temperature around the liquid pipe 5 from the outside air temperature sensor 31 and takes in information on the temperature of the liquid refrigerant flowing through the liquid pipe 5 from the refrigerant temperature sensor 32.
(S3)
Compare the outside air temperature and the liquid refrigerant temperature. When outside temperature is more than liquid refrigerant temperature, it shifts to Step S4. Otherwise, the process proceeds to step S5.
(S4)
The valve 15 of the bypass circuit 11 is opened, the amount of refrigerant flowing through the bypass circuit 11 is increased, and the liquid refrigerant temperature is increased.
(S5)
The valve 15 of the bypass circuit 11 is closed, the amount of refrigerant flowing through the bypass circuit 11 is reduced, the liquid refrigerant temperature is lowered, and the liquid refrigerant temperature is adjusted to the vicinity of the outside air temperature.

  As described above, the valve 15 and the flow rate control device 33 are provided in the bypass circuit 11 to control the opening degree of the valve 15, and the liquid refrigerant condensed by the condenser 6 and the supercooled liquid added by the heat exchanger 13. By combining the refrigerant, the temperature of the liquid refrigerant can be made higher than the outside air temperature around the liquid pipe 5. Thereby, it is possible to select whether or not to heat-insulate the liquid pipe 5 to prevent condensation, and to obtain a refrigeration and air-conditioning apparatus that can flexibly respond to the cost and delivery date burden borne by the customer. Can do.

  Furthermore, since the flow rate control device 33 of the bypass circuit 11 is provided and the amount of refrigerant flowing through the circuit bypassing the heat exchanger 13 is controlled, the liquid refrigerant temperature can be controlled near the outside air temperature, and the liquid pipe 5 It is possible to obtain a refrigeration air conditioner that can prevent condensation.

  In the fourth embodiment, the opening degree of the valve 15 of the bypass circuit 11 is controlled by comparing the outside air temperature and the liquid refrigerant temperature. However, the present invention is not limited to this, for example, the outside air temperature sensor 31 Instead, a dew point temperature of the outside air may be obtained using a dew point meter, and the opening degree of the valve 15 of the bypass circuit 11 may be controlled by comparing the dew point temperature of the outside air with the liquid refrigerant temperature.

  DESCRIPTION OF SYMBOLS 1 Compressor, 1a Injection piping, 2 Means for cooling refrigerant using first heat source lower than outside air dew point temperature, 3 Usage side expansion valve, 4 Usage side heat exchanger, 5 Liquid piping, 6 Condenser, 7 Gas Piping, 11 Bypass circuit, 12 Throttle device, 13 Heat exchanger, 14 Refrigerant piping, 15 Valve, 16 Branch, 20 On-site connection liquid piping, 21 On-site connection gas piping, 30 Supercooling refrigerant circuit, 31 Outside air temperature sensor, 32 Refrigerant temperature sensor, 33 flow rate control device, 100 refrigerant circuit.

Claims (9)

A main refrigerant circuit in which a compressor, a condenser, a first pressure reducing device, and an evaporator are annularly connected via a refrigerant pipe;
A supercooled refrigerant circuit comprising a heat exchanger for further cooling the refrigerant on the outlet side of the condenser;
A bypass circuit connected between a refrigerant pipe upstream of the heat exchanger and a refrigerant pipe downstream of the heat exchanger, and bypassing the heat exchanger;
With
The bypass circuit bypasses the heat exchanger and sends a part of the refrigerant condensed in the condenser to a refrigerant pipe on the downstream side of the heat exchanger.
Refrigeration air conditioner. The compressor has an injection pipe,
The supercooling refrigerant circuit is
A second decompression device for decompressing the first refrigerant branched from between the outlet of the bypass circuit and the first decompression device;
The heat exchanger that performs heat exchange between the first refrigerant sent from the second decompression device and the second refrigerant that has exited the condenser, and supercools the second refrigerant;
With
Sending the first refrigerant heat-exchanged by the heat exchanger to an injection pipe of the compressor;
The refrigerating and air-conditioning apparatus according to claim 1 . The second pressure reducing device is a variable flow rate adjusting valve that controls the flow rate.
The refrigerating and air-conditioning apparatus according to claim 2 . The bypass circuit is one of the refrigerant condensed in the condenser so that the temperature of the refrigerant in the refrigerant pipe between the condenser and the first pressure reducing device is higher than the dew point temperature of the surrounding outside air. Part to the refrigerant pipe downstream of the heat exchanger,
The refrigeration air conditioner as described in any one of Claims 1-3 . The bypass circuit includes a part of the refrigerant condensed in the condenser so that the temperature of the refrigerant in the refrigerant pipe between the condenser and the first pressure reducing device is higher than the temperature of the surrounding outside air. To the refrigerant pipe downstream of the heat exchanger,
The refrigeration air conditioner as described in any one of Claims 1-3 . The bypass circuit includes a variable flow rate adjustment valve that adjusts the flow rate of the refrigerant or a switching valve that can be opened and closed.
The refrigeration air conditioner as described in any one of Claims 1-5 . A refrigerant temperature sensor for detecting the temperature of the refrigerant in the refrigerant pipe between the condenser and the first pressure reducing device;
An outside air temperature sensor for detecting the outside air temperature;
A flow rate control device that controls the flow rate adjustment valve or the switching valve based on the temperature of the refrigerant detected by the refrigerant temperature sensor and the temperature of the outside air detected by the outside air temperature sensor;
Further comprising
The refrigerating and air-conditioning apparatus according to claim 6 . The flow rate control device adjusts the flow rate of the refrigerant flowing through the bypass circuit so that the refrigerant in the liquid pipe is higher than the dew point temperature of the surrounding outside air.
The refrigerating and air-conditioning apparatus according to claim 7 . The flow rate control device adjusts the flow rate of the refrigerant flowing through the bypass circuit so that the refrigerant in the liquid pipe is higher than the temperature of the ambient outside air.
The refrigerating and air-conditioning apparatus according to claim 7 .

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