JP2011052884A - Refrigerating air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating air conditioner suppressing increase in condensation pressure when high temperature water is taken out and having good operating efficiency and high reliability. <P>SOLUTION: The refrigerating air conditioner includes a supercooling heat exchanger 3 inserted between a condenser 2 and an electronic type expansion valve 4 of a refrigerating cycle device 31 and cooling a refrigerant from the condenser 2 by exchanging heat with a low temperature refrigerant. Based on refrigerant pressure on the discharge side of the compressor 1 detected by a pressure sensor 11 and refrigerant temperature on the outlet side of the supercooling heat exchanger 3 detected by a thermistor 21, a supercooling degree of the supercooling heat exchanger 3 is calculated, and an opening of the electronic type expansion valve 4 is controlled so that the supercooling degree becomes a first predetermined value. A low pressure gas liquid two-phase refrigerant from the electronic type expansion valve 4 is used as the low temperature refrigerant of the supercooling heat exchanger 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a refrigeration air conditioner using a refrigeration cycle apparatus used for, for example, hot water supply equipment, heating equipment, heating equipment, drying equipment, and the like.

  In a conventional refrigeration air conditioner, a compressor, a condenser, a gas-liquid separator, a supercooling heat exchanger, an expansion valve, and an evaporator are sequentially connected by a refrigerant pipe. In some cases, a capillary tube and an on-off valve are connected by a bypass pipe between the bottom of the vessel and the suction side of the compressor.

  In the above-described refrigeration air conditioner, the refrigerant compressed by the compressor is heat-exchanged by the condenser to become a high-pressure gas-liquid two-phase refrigerant and flows into the gas-liquid separator. The refrigerant exiting this gas-liquid separator is cooled by the low-pressure gas-liquid two-phase refrigerant before entering the evaporator in the supercooling heat exchanger, enters a supercooled state, flows into the expansion valve, and is decompressed here. It becomes a low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the evaporator through the supercooling heat exchanger and becomes low-pressure vapor refrigerant and reaches the suction side of the compressor. On the other hand, a part of the liquid refrigerant separated by the gas-liquid separator flows into the suction side of the compressor through the capillary tube and the on-off valve, joins with the low-pressure vapor refrigerant from the evaporator, and is compressed again by the compressor. (For example, refer to Patent Document 1).

JP-A-10-259959 (page 4, FIG. 1)

  In the conventional refrigeration air conditioner described above, a gas-liquid separator and a supercooling heat exchanger are provided on the outlet side of the condenser, so that the refrigerant state on the outlet side of the condenser is a gas-liquid two-phase state or a saturated liquid state. It becomes. Therefore, the condensation pressure can be kept low even during hot water supply operation under the condition of high-temperature water, and efficient operation can be performed. However, in the case of a general control method in which the refrigerant superheat degree on the outlet side of the evaporator is controlled to be constant, the refrigerant on the outlet side of the supercooling heat exchanger is not necessarily in a supercooled state depending on operating conditions. In some cases, the refrigerant on the outlet side of the supercooling heat exchanger is in a gas-liquid two-phase state.

  When the refrigerant on the outlet side of the supercooling heat exchanger enters a gas-liquid two-phase state, the two-phase refrigerant passes through the expansion valve, so the stability of the refrigeration cycle deteriorates and pressure and temperature hunting occurs. There is a possibility that the reliability of the refrigeration air conditioner will deteriorate. Further, when the gas-liquid two-phase refrigerant passes through the expansion valve, the flow noise and vibration of the refrigerant increase, and the noise of the refrigeration air conditioner may increase.

  The present invention has been made in order to solve the above-described problems. In particular, the present invention provides a refrigeration / air-conditioning apparatus that suppresses an increase in condensation pressure particularly when high-temperature water is taken out, has high operating efficiency, and is highly reliable. For the purpose.

  A refrigeration air conditioner according to the present invention includes a compressor, a condenser, a first decompression device, a refrigeration cycle device in which an evaporator is sequentially connected by a refrigerant pipe, and between the condenser of the refrigeration cycle device and the first decompression device. The subcooled heat exchanger that exchanges heat from the condenser with the low-temperature refrigerant to cool it, the refrigerant pressure detection means that detects the pressure of the refrigerant discharged from the compressor, and the subcooled heat exchanger First refrigerant temperature detection means for detecting the temperature of the refrigerant to be performed, a supercooling heat exchanger based on the refrigerant pressure detected by the refrigerant pressure detection means and the refrigerant temperature detected by the first refrigerant temperature detection means And a control device for controlling the degree of opening of the first pressure reducing device so that the degree of supercooling becomes a first predetermined value.

  In the present invention, a supercooling heat exchanger is provided on the outlet side of the condenser, and the first pressure reducing device is opened so that the degree of supercooling of the refrigerant flowing out of the supercooling heat exchanger becomes a first predetermined value. Control the degree. Therefore, the refrigerant on the outlet side of the condenser can be in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the first decompression device can be in a supercooled liquid state under any operating condition or load condition. . As a result, it is possible to suppress an increase in the condensation pressure, particularly when high-temperature water is taken out, and the operation efficiency is improved.In addition, the stability of the refrigeration cycle is improved, and the flow noise of the refrigerant and abnormal vibration are also generated. And a low-noise refrigeration air conditioner can be provided.

It is a block diagram of the refrigerant circuit which shows the refrigeration air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a block diagram of the refrigerant circuit which shows the refrigerating air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a block diagram of the refrigerant circuit which shows the refrigeration air conditioning apparatus which concerns on Embodiment 3 of this invention. It is a block diagram of the refrigerant circuit which shows the refrigerating air conditioning apparatus which concerns on Embodiment 4 of this invention. It is a block diagram of the refrigerant circuit which shows the refrigerating air conditioning apparatus which concerns on Embodiment 5 of this invention. It is a block diagram of the refrigerant circuit which shows the refrigerating air conditioning apparatus which concerns on Embodiment 6 of this invention. It is a block diagram of the refrigerant circuit which shows the refrigerating air conditioning apparatus which concerns on Embodiment 7 of this invention.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 1 of the present invention.
In FIG. 1, a refrigeration cycle apparatus 31 of a refrigeration air conditioner is configured by sequentially connecting a compressor 1, a condenser 2, an electronic expansion valve 4 serving as a first decompression device, and an evaporator 5 through a refrigerant pipe. . Between the condenser 2 and the electronic expansion valve 4, supercooling heat that cools the refrigerant (high-pressure gas-liquid two-phase refrigerant) from the condenser 2 by exchanging heat with the low-temperature refrigerant (low-pressure gas-liquid two-phase refrigerant). An exchanger 3 is provided.

  The condenser 2 is composed of, for example, a plate heat exchanger, and heats inflowing water with a condensed refrigerant during heating, and supplies the water as, for example, high-temperature water of 60 ° C. The evaporator 5 is composed of, for example, a plate fin and tube heat exchanger, and exchanges heat with air. The supercooling heat exchanger 3 is composed of, for example, a plate heat exchanger, and the high-pressure gas-liquid two-phase refrigerant from the condenser 2 by the low-pressure gas-liquid two-phase refrigerant before leaving the electronic expansion valve 4 and entering the evaporator 5. It is configured to cool.

  A pressure sensor 11 that is a refrigerant pressure detection means is attached to the refrigerant pipe between the compressor 1 and the condenser 2, and the refrigerant pipe on the outlet side of the supercooling heat exchanger 3 is connected to the refrigerant pipe at the first refrigerant temperature detection means. A certain thermistor 21 is attached. The pressure sensor 11 detects the pressure of the high-pressure gas-liquid two-phase refrigerant discharged from the compressor 1, and the thermistor 21 detects the temperature of the refrigerant flowing out from the supercooling heat exchanger 3.

  The control device 10 calculates the saturated liquid temperature from the refrigerant pressure (pressure of the high-pressure gas-liquid two-phase refrigerant) on the discharge side of the compressor 1 detected by the pressure sensor 11, and the saturated liquid temperature and the thermistor 21 detect the saturated liquid temperature. The degree of supercooling on the outlet side of the supercooling heat exchanger 3 is calculated from the refrigerant temperature difference on the outlet side of the supercooling heat exchanger 3. Further, the control device 10 compares the calculated degree of supercooling with a first predetermined value (for example, 5 ° C.), and when there is a difference from the predetermined value, the electronic device is adjusted so that the degree of supercooling becomes 5 ° C. The opening degree of the expansion valve 4 is controlled.

  R410A is used as the refrigerant of the refrigeration air conditioner. The design pressure of this refrigeration air conditioner is designed to be 4.17 MPa with a standard condensation temperature of 65 ° C. That is, the maximum condensation temperature of the refrigeration cycle is 65 ° C. from the viewpoint of design pressure. For example, in order to set the outlet water temperature of the condenser 2 to 60 ° C., it is necessary to use the condenser 2 efficiently and to use the condensation temperature at 65 ° C. or less.

Next, the operation of the first embodiment will be described.
The high-pressure vapor refrigerant compressed by the compressor 1 is condensed in the condenser 2 and flows into the supercooling heat exchanger 3 as a high-pressure gas-liquid two-phase refrigerant. The high-pressure gas-liquid two-phase refrigerant is cooled by the low-pressure gas-liquid two-phase refrigerant before entering the evaporator 5 in the supercooling heat exchanger 3 and flows into the electronic expansion valve 4 in a supercooled liquid state. . The high-pressure supercooled liquid refrigerant is depressurized in the electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the supercooling heat exchanger 3, and the high-pressure gas-liquid two-phase refrigerant from the condenser 2 is It flows into the evaporator 5 while cooling. The low-pressure gas-liquid two-phase refrigerant that has flowed into the evaporator 5 exchanges heat with air to become a low-pressure vapor refrigerant, and is sucked into the compressor 1 and compressed again.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature in the supercooled liquid state on the outlet side of the supercooling heat exchanger 3 detected by the thermistor 21, and performs supercooling from the previously calculated saturated liquid temperature and the difference between the refrigerant temperatures. The degree of supercooling on the outlet side of the heat exchanger 3 is calculated. Then, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and if there is a difference between the first predetermined value, the degree of supercooling is 5 ° C. The opening degree of the electronic expansion valve 4 is controlled. For example, when the calculated degree of supercooling is lower than 5 ° C., the control device 10 reduces the degree of opening of the electronic expansion valve 4 so that the degree of supercooling rises to 5 ° C., and the degree of supercooling exceeds 5 ° C. Is higher, the opening degree of the electronic expansion valve 4 is increased so that the degree of supercooling is lowered to 5 ° C.

Here, the case where the refrigeration air conditioner of Embodiment 1 is applied to, for example, an air-cooled heat pump chiller will be described.
The heating operation range in the conventional air-cooled heat pump chiller is generally an outside air temperature of −15 ° C. to 25 ° C., an outlet water temperature of 25 ° C. to 55 ° C., and a capacity control range of 10 to 100%. In the applied air-cooled heat pump chiller, the outside air temperature and the capability control range are the same, and the outlet water temperature can be expanded to 25 ° C to 60 ° C. This is because when the outside air temperature, the outlet water temperature, and the capacity change, the heat exchange amount in the condenser 2 and the supercooling heat exchanger 3 also changes. It has been difficult to keep the gas-liquid two-phase refrigerant in a saturated liquid state and always maintain the refrigerant on the outlet side of the supercooling heat exchanger 3 at a predetermined supercooling degree.

  In the air-cooled heat pump chiller to which the first embodiment is applied, the opening degree of the electronic expansion valve 4 is controlled by the control device 10 so that the degree of supercooling of the refrigerant flowing out of the supercooling heat exchanger 3 is always 5 ° C. I have control. Therefore, the refrigerant passing through the electronic expansion valve 4 can always maintain the supercooled liquid state even when the operating conditions and load conditions change. As a result, the outlet side of the condenser 2 is also in the saturated liquid state or the high-pressure gas-liquid state. A two-phase state can be maintained. Therefore, the upper limit of outlet temperature can be expanded from the conventional 55 degreeC to 60 degreeC.

  As described above, in Embodiment 1, the supercooling heat exchanger 3 is provided on the outlet side of the condenser 2, and the supercooling heat exchanger is removed from the condenser 2 by the low-pressure gas-liquid two-phase refrigerant on the inlet side of the evaporator 5. The high-pressure gas-liquid two-phase refrigerant flowing into 3 is cooled. Further, the opening degree of the electronic expansion valve 4 is controlled so that the degree of supercooling on the outlet side of the supercooling heat exchanger 3 is always 5 ° C. As a result, the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the electronic expansion valve 4 is in a supercooled liquid state under any operating conditions or load conditions. be able to. Therefore, even in a high-temperature hot water supply operation in which the outlet water temperature of the condenser 2 is 60 ° C., the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state, and the condenser 2 has supercooling with poor heat transfer characteristics. There is no liquid. Therefore, the condensing pressure can be lowered, the upper limit temperature can be increased with respect to the conventional upper limit of the outlet water temperature of 55 ° C., and the condensing pressure can be lowered, so that an efficient operation is possible. .

  Furthermore, since the opening degree of the electronic expansion valve 4 is controlled by the control device 10 so that the degree of supercooling of the refrigerant flowing out of the supercooling heat exchanger 3 is always 5 ° C., the electronic expansion valve 4 passes through. The refrigerant to be maintained can always maintain the state of the supercooled liquid even if the operating condition or the load condition changes. Therefore, the stability of the refrigeration cycle is improved, and there is no generation of refrigerant flow noise or abnormal vibration, and a refrigeration air conditioner with low noise can be realized.

  In the first embodiment, an example in which R410A is used as the refrigerant is shown, but the present invention is not limited to this. For example, by using R134a having a relatively high normal boiling point, the condensation temperature can be increased even at the same condensation pressure, and the outlet water temperature of the condenser 2 can be increased to, for example, 80 ° C.

  Further, HFO-1234fy (2,3,3,3-tetrafluoropropene) or HFO-1234ze (1,3,3,3 tetrafluoropentane) may be used as the refrigerant. Furthermore, a mixed refrigerant of HFO-1234fy and a refrigerant such as R134a, R125, R32, R152a may be used. These HFO refrigerants and mixed refrigerants thereof can provide a refrigeration air conditioner that has a low global warming potential and is friendly to the global environment.

Embodiment 2. FIG.
FIG. 2 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 2 of the present invention.
In FIG. 2, a refrigeration cycle device 31 of a refrigeration air conditioner is configured by sequentially connecting a compressor 1, a condenser 2, an electronic expansion valve 4 as a first decompression device, and an evaporator 5 through a refrigerant pipe. . Between the condenser 2 and the electronic expansion valve 4, a supercooling heat exchanger 3 that cools the refrigerant (high-pressure gas-liquid two-phase refrigerant) from the condenser 2 by exchanging heat with the low-temperature refrigerant (low-pressure vapor refrigerant). Is provided.

  The condenser 2 and the supercooling heat exchanger 3 described above are plate heat exchangers, and the evaporator 5 is a plate fin and tube heat exchanger. The supercooling heat exchanger 3 is configured to cool the high-pressure gas-liquid two-phase refrigerant from the condenser 2 with the low-pressure vapor refrigerant before leaving the evaporator 5 and entering the compressor 1.

  A pressure sensor 11 that detects the pressure of the refrigerant discharged from the compressor 1 (pressure of the high-pressure gas-liquid two-phase refrigerant) is attached to the refrigerant pipe between the compressor 1 and the condenser 2, and is a supercooling heat exchanger. A thermistor 21 (first refrigerant temperature detecting means) for detecting the temperature of the refrigerant flowing out from the supercooling heat exchanger 3 is attached to the refrigerant pipe on the outlet side of the No. 3 outlet.

  The control device 10 calculates the saturated liquid temperature from the refrigerant pressure on the discharge side of the compressor 1 detected by the pressure sensor 11, and outputs the saturated liquid temperature and the outlet side of the supercooling heat exchanger 3 detected by the thermistor 21. The degree of supercooling on the outlet side of the supercooling heat exchanger 3 is calculated from the difference in refrigerant temperature. Further, the control device 10 compares the calculated degree of supercooling with a first predetermined value (5 ° C.), and if there is a difference between the predetermined value, the electronic expansion is performed so that the degree of supercooling becomes 5 ° C. The opening degree of the valve 4 is controlled.

Next, the operation of the second embodiment will be described.
The high-pressure vapor refrigerant compressed by the compressor 1 is condensed in the condenser 2 and flows into the supercooling heat exchanger 3 as a high-pressure gas-liquid two-phase refrigerant. The high-pressure gas-liquid two-phase refrigerant is cooled by the low-pressure vapor refrigerant discharged from the evaporator 5 in the supercooling heat exchanger 3 and flows into the electronic expansion valve 4 in a high-pressure supercooled liquid state. The high-pressure supercooled liquid refrigerant is depressurized in the electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the evaporator 5, and exchanges heat with air to become a low-pressure vapor refrigerant. The low-pressure vapor refrigerant enters the supercooling heat exchanger 3, cools the high-pressure gas-liquid two-phase refrigerant from the condenser 2, is sucked into the compressor 1, and is compressed again by the compressor 1.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature in the supercooled liquid state on the outlet side of the supercooling heat exchanger 3 detected by the thermistor 21, and performs supercooling from the previously calculated saturated liquid temperature and the difference between the refrigerant temperatures. The degree of supercooling on the outlet side of the heat exchanger 3 is calculated. Then, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and when there is a difference from the first predetermined value, the degree of supercooling is 5 ° C. The opening degree of the electronic expansion valve 4 is controlled. For example, when the calculated degree of supercooling is lower than 5 ° C., the control device 10 reduces the degree of opening of the electronic expansion valve 4 so that the degree of supercooling rises to 5 ° C., and the degree of supercooling exceeds 5 ° C. Is higher, the opening degree of the electronic expansion valve 4 is increased so that the degree of supercooling is lowered to 5 ° C.

  As described above, according to Embodiment 2, the supercooling heat exchanger 3 is provided on the outlet side of the condenser 2, and the high-pressure gas-liquid two on the outlet side of the condenser 2 by the low-pressure vapor refrigerant on the outlet side of the evaporator 5. Cool the phase refrigerant. Further, the opening degree of the electronic expansion valve 4 is controlled so that the degree of supercooling on the outlet side of the supercooling heat exchanger 3 is always 5 ° C. As a result, the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the electronic expansion valve 4 is in a supercooled liquid state under any operating conditions or load conditions. be able to. Therefore, even in a high-temperature hot water supply operation in which the outlet water temperature of the condenser 2 is 60 ° C., the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state, and the condenser 2 has supercooling with poor heat transfer characteristics. There is no liquid. Therefore, the condensing pressure can be lowered, the upper limit temperature can be increased with respect to the conventional upper limit of the outlet water temperature of 55 ° C., and the condensing pressure can be lowered, so that an efficient operation is possible.

  Furthermore, since the opening degree of the electronic expansion valve 4 is controlled by the control device 10 so that the degree of supercooling of the refrigerant on the outlet side of the supercooling heat exchanger 3 is always 5 ° C., the electronic expansion valve 4 is The refrigerant that passes through can always maintain the state of the supercooled liquid even if the operating conditions and load conditions change. Therefore, the stability of the refrigeration cycle is improved, and there is no generation of refrigerant flow noise or abnormal vibration, and a refrigeration air conditioner with low noise can be realized.

Embodiment 3 FIG.
FIG. 3 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 3 of the present invention.
In FIG. 3, a refrigeration cycle device 31 of a refrigeration air conditioner is configured by sequentially connecting a compressor 1, a condenser 2, a first electronic expansion valve 4 as a first decompression device, and an evaporator 5 through a refrigerant pipe. ing. Further, in the refrigeration cycle apparatus, the refrigerant (high pressure gas-liquid two-phase refrigerant) from the condenser 2 is heated between the condenser 2 and the first electronic expansion valve 4 and the low-temperature refrigerant (low-pressure gas-liquid two-phase refrigerant) and heat. A supercooling heat exchanger 3 that replaces and cools is provided. Further, a second electronic expansion valve 6 (from the refrigerant pipe inserted between the first electronic expansion valve 4 and the supercooling heat exchanger 3 to the suction side of the compressor 1 through the supercooling heat exchanger 3 ( A bypass pipe 7 is provided for bypassing via a second decompression device.

  The condenser 2 and the subcooling heat exchanger 3 are plate heat exchangers, and the evaporator 5 is a plate fin and tube heat exchanger. The supercooling heat exchanger 3 is configured to cool the high-pressure gas-liquid two-phase refrigerant from the condenser 2 with the low-pressure gas-liquid two-phase refrigerant decompressed by the second electronic expansion valve 6. The low-pressure gas-liquid two-phase refrigerant from the second electronic expansion valve 6 that has exited the supercooling heat exchanger 3 is introduced to the suction side of the compressor 1 through the bypass pipe 7.

  A pressure sensor 11 for detecting the refrigerant pressure on the discharge side of the compressor 1 (pressure of the high-pressure gas-liquid two-phase refrigerant) is attached to the refrigerant pipe between the compressor 1 and the condenser 2, and the supercooling heat exchanger 3. The thermistor 21 (first refrigerant temperature detecting means) for detecting the refrigerant temperature on the outlet side of the supercooling heat exchanger 3 is attached to the refrigerant pipe on the outlet side of the refrigerant.

  The control device 10 calculates the saturated liquid temperature from the refrigerant pressure on the discharge side of the compressor 1 detected by the pressure sensor 11, and outputs the saturated liquid temperature and the outlet side of the supercooling heat exchanger 3 detected by the thermistor 21. The degree of supercooling on the outlet side of the supercooling heat exchanger 3 is calculated from the difference in refrigerant temperature. Further, the control device 10 compares the calculated degree of supercooling with a first predetermined value (5 ° C.), and if there is a difference between the predetermined value, the first electronic device is set so that the degree of supercooling becomes 5 ° C. The opening degree of the expansion valve 4 is controlled.

Next, the operation of the third embodiment will be described.
The high-pressure vapor refrigerant compressed by the compressor 1 is condensed by the condenser 2 and becomes a high-pressure gas-liquid two-phase refrigerant and flows into the supercooling heat exchanger 3. The high-pressure gas-liquid two-phase refrigerant is cooled by the low-pressure gas-liquid two-phase refrigerant that has exited from the second electronic expansion valve 6 in the supercooling heat exchanger 3, and becomes a high-pressure supercooled liquid state to form the first electrons. Flows into the expansion valve 4. The high-pressure supercooled liquid refrigerant is depressurized in the first electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the evaporator 5, and exchanges heat with air to become a low-pressure vapor refrigerant. The low-pressure vapor refrigerant is sucked into the compressor 1 and compressed again by the compressor 1.

  A part of the high-pressure supercooled liquid refrigerant exiting the supercooling heat exchanger 3 is depressurized to a low pressure by the second electronic expansion valve 6 to become a low-pressure gas-liquid two-phase refrigerant, and the supercooling heat exchanger 3. To exchange heat with the high-pressure gas-liquid two-phase refrigerant from the condenser 2. The low-pressure gas-liquid two-phase refrigerant that has passed through the supercooling heat exchanger 3 merges with the low-pressure vapor refrigerant that has exited the evaporator 4 through the bypass pipe 7 and is sucked into the compressor 1 and compressed again by the compressor 1. Is done.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature in the supercooled liquid state on the outlet side of the supercooling heat exchanger 3 detected by the thermistor 21, and performs supercooling from the previously calculated saturated liquid temperature and the difference between the refrigerant temperatures. The degree of supercooling on the outlet side of the heat exchanger 3 is calculated. Then, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and when there is a difference from the first predetermined value, the degree of supercooling is 5 ° C. The opening degree of the first electronic expansion valve 4 is controlled. For example, when the calculated degree of supercooling is lower than 5 ° C., the control device 10 reduces the opening degree of the first electronic expansion valve 4 so that the degree of supercooling increases to 5 ° C., and the degree of supercooling is 5 When it is higher than ° C., the opening degree of the first electronic expansion valve 4 is increased so that the degree of supercooling is lowered to 5 ° C.

  As described above, according to the third embodiment, the supercooling heat exchanger 3 is provided on the outlet side of the condenser 2, and the low-pressure gas-liquid two-phase in which a part of the refrigerant exiting the supercooling heat exchanger 3 is decompressed. The high-pressure gas-liquid two-phase refrigerant from the condenser 2 is cooled by the refrigerant. Further, the opening degree of the first electronic expansion valve 4 is controlled so that the degree of supercooling on the outlet side of the supercooling heat exchanger 3 is always 5 ° C. As a result, the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the first electronic expansion valve 4 is in a supercooled liquid state under any operating condition or load condition. It can be. Therefore, even in a high-temperature hot water supply operation in which the outlet water temperature of the condenser 2 is 60 ° C., the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state, and the condenser 2 has supercooling with poor heat transfer characteristics. There is no liquid. Therefore, the condensing pressure can be lowered, the upper limit temperature can be increased with respect to the conventional upper limit of the outlet water temperature of 55 ° C., and the condensing pressure can be lowered, so that an efficient operation is possible.

  Further, since the opening degree of the first electronic expansion valve 4 is controlled by the control device 10 so that the degree of supercooling of the refrigerant on the outlet side of the supercooling heat exchanger 3 is always 5 ° C., the first electronic type The refrigerant passing through the expansion valve 4 can always maintain the state of the supercooled liquid even if the operation condition or load condition changes. Therefore, the stability of the refrigeration cycle is improved, and there is no generation of refrigerant flow noise or abnormal vibration, and a refrigeration air conditioner with low noise can be realized.

  Further, as the low-pressure refrigerant of the supercooling heat exchanger 3, a low-pressure gas-liquid two-phase refrigerant obtained by decompressing a part of the high-pressure supercooled liquid refrigerant that has exited the supercooling heat exchanger 3 is used. Therefore, the refrigerant on the inlet side of the second electronic expansion valve 6 can be surely brought into a liquid state as compared with a case where a part of the high-pressure gas-liquid two-phase refrigerant that has exited the condenser 2 is decompressed. Moreover, the heat exchange amount of the supercooling heat exchanger 3 can be ensured reliably, and the supercooling degree of the supercooling heat exchanger 3 can be controlled reliably. In addition, since the refrigerant on the inlet side of the second electronic expansion valve 6 can be reliably used as a liquid refrigerant, the stability of the refrigeration cycle in the second electronic expansion valve 6 is improved, and the refrigerant flow noise and There is no occurrence of abnormal vibration, and a highly reliable refrigeration air conditioner can be provided.

  In addition, in Embodiment 3, although the example which always supplies a low-temperature refrigerant | coolant to the supercooling heat exchanger 3 was demonstrated, it is not limited to this. For example, the second electronic expansion valve 6 may be opened when the condensing pressure becomes higher than a predetermined value or when the outlet water temperature of the condenser 2 becomes higher than a predetermined value. In that case, a low-pressure gas-liquid two-phase refrigerant is caused to flow through the supercooling heat exchanger 3 so that the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state.

Embodiment 4 FIG.
FIG. 4 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 4 of the present invention.
In FIG. 4, a refrigeration cycle device 31 of a refrigeration air conditioner is configured by sequentially connecting a compressor 1, a condenser 2, a first electronic expansion valve 4 as a first pressure reducing device, and an evaporator 5 through a refrigerant pipe. ing. Further, in the refrigeration cycle apparatus, the refrigerant (high pressure gas-liquid two-phase refrigerant) from the condenser 2 is heated between the condenser 2 and the first electronic expansion valve 4 and the low-temperature refrigerant (intermediate pressure gas-liquid two-phase refrigerant) and heat. A supercooling heat exchanger 3 that replaces and cools is provided. Further, a second electronic expansion valve is connected from the refrigerant pipe inserted between the first electronic expansion valve 4 and the supercooling heat exchanger 3 to the intermediate pressure chamber in the compressor 1 via the supercooling heat exchanger 3. A bypass pipe 7 for bypassing via 6 (second decompression device) is provided. The second electronic expansion valve 6 can be opened and closed.

  The condenser 2 is composed of, for example, a plate heat exchanger, and heats inflowed water with a condensed refrigerant during heating, and supplies the water as, for example, high-temperature water of 60 ° C. The evaporator 5 is composed of, for example, a plate fin and tube heat exchanger, and exchanges heat with air. The supercooling heat exchanger 3 includes, for example, a plate heat exchanger, and cools the high-pressure gas-liquid two-phase refrigerant from the condenser 2 by the intermediate-pressure gas-liquid two-phase refrigerant decompressed by the second electronic expansion valve 6. It is configured. The intermediate-pressure gas-liquid two-phase refrigerant exiting the supercooling heat exchanger 3 is introduced into the intermediate pressure chamber in the compressor 1 through the bypass pipe 7.

  A pressure sensor 11 for detecting the refrigerant pressure on the discharge side of the compressor 1 (pressure of the high-pressure gas-liquid two-phase refrigerant) is attached to the refrigerant pipe between the compressor 1 and the condenser 2, and the supercooling heat exchanger 3. The thermistor 21 (first refrigerant temperature detecting means) for detecting the refrigerant temperature on the outlet side of the supercooling heat exchanger 3 is attached to the refrigerant pipe on the outlet side of the refrigerant.

  In addition to controlling the opening degree of the first electronic expansion valve 4, the control device 10 in the fourth embodiment opens and closes the second electronic expansion valve 6 based on the refrigerant pressure on the discharge side of the compressor 1. It comes to control.

Next, the operation of the fourth embodiment will be described.
The high-pressure vapor refrigerant compressed by the compressor 1 is condensed in the condenser 2 and flows into the supercooling heat exchanger 3 as a high-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is cooled by the intermediate-pressure gas-liquid two-phase refrigerant that has exited the second electronic expansion valve 6 in the supercooling heat exchanger 3, and becomes a high-pressure supercooled liquid state. It flows into the expansion valve 4. The high-pressure supercooled liquid refrigerant is depressurized in the first electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the evaporator 5, and exchanges heat with air to become a low-pressure vapor refrigerant. The low-pressure vapor refrigerant is sucked into the compressor 1 and compressed again by the compressor 1.

  Further, a part of the high-pressure supercooled liquid refrigerant exiting the supercooling heat exchanger 5 is decompressed to an intermediate pressure by the second electronic expansion valve 6 to become an intermediate-pressure gas-liquid two-phase refrigerant, and the supercooling heat exchanger 3 and exchanges heat with the high-pressure gas-liquid two-phase refrigerant from the condenser 2. The intermediate-pressure gas-liquid two-phase refrigerant via the supercooling heat exchanger 3 flows into the intermediate pressure chamber in the compressor 1 through the bypass pipe 7, and the low-pressure vapor refrigerant from the evaporator 5 in the compressor 1. It merges and is compressed again by the compressor 1.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature in the supercooled liquid state on the outlet side of the supercooling heat exchanger 3 detected by the thermistor 21, and performs supercooling from the previously calculated saturated liquid temperature and the difference between the refrigerant temperatures. The degree of supercooling on the outlet side of the heat exchanger 3 is calculated. Then, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and when there is a difference from the first predetermined value, the degree of supercooling is 5 ° C. The opening degree of the first electronic expansion valve 4 is controlled. For example, when the calculated degree of supercooling is lower than 5 ° C., the control device 10 reduces the opening degree of the first electronic expansion valve 4 so that the degree of supercooling increases to 5 ° C., and the degree of supercooling is 5 When it is higher than ° C., the opening degree of the first electronic expansion valve 4 is increased so that the degree of supercooling is lowered to 5 ° C.

  Further, the control device 10 determines whether or not the refrigerant pressure on the discharge side of the compressor 1 detected by the pressure sensor 11 is a second predetermined value, for example, 3.5 MPa or more, and the refrigerant pressure is 3.5 MPa or more. When the second electronic expansion valve 6 is opened. At this time, the above-described intermediate-pressure gas-liquid two-phase refrigerant flows into the supercooling heat exchanger 3. When the pressure on the discharge side of the compressor 1 is lower than 3.5 MPa, the second electronic expansion valve 6 is fully closed so that the intermediate-pressure gas-liquid two-phase refrigerant is not supplied to the supercooling heat exchanger 3.

  As described above, according to the fourth embodiment, the intermediate pressure air in which the supercooling heat exchanger 3 is provided on the outlet side of the condenser 2 and a part of the refrigerant exiting the supercooling heat exchanger 3 is reduced to the intermediate pressure. The high-pressure gas-liquid two-phase refrigerant from the condenser 2 is cooled by the liquid two-phase refrigerant. Further, the opening degree of the first electronic expansion valve 4 is controlled so that the degree of supercooling on the outlet side of the supercooling heat exchanger 3 is always 5 ° C. As a result, the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the first electronic expansion valve 4 is in a supercooled liquid state under any operating condition or load condition. It can be. Therefore, even in a high-temperature hot water supply operation in which the outlet water temperature of the condenser 2 is 60 ° C., the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state, and the condenser 2 has supercooling with poor heat transfer characteristics. There is no liquid. Therefore, the condensing pressure can be lowered, the upper limit temperature can be increased with respect to the conventional upper limit of the outlet water temperature of 55 ° C., and the condensing pressure can be lowered, so that an efficient operation is possible.

  Further, since the opening degree of the first electronic expansion valve 4 is controlled by the control device 10 so that the degree of supercooling of the refrigerant on the outlet side of the supercooling heat exchanger 3 is always 5 ° C., the first electronic type The refrigerant passing through the expansion valve 4 can always maintain the state of the supercooled liquid even if the operation condition or load condition changes. Therefore, the stability of the refrigeration cycle is improved, and there is no generation of refrigerant flow noise or abnormal vibration, and a refrigeration air conditioner with low noise can be realized.

  Further, as the intermediate pressure refrigerant of the supercooling heat exchanger 3, an intermediate pressure gas-liquid two-phase refrigerant obtained by reducing a part of the high pressure supercooled liquid refrigerant exiting the supercooling heat exchanger 3 to an intermediate pressure is used. Therefore, the refrigerant on the inlet side of the second electronic expansion valve 6 can be surely brought into a liquid state as compared with a case where a part of the high-pressure gas-liquid two-phase refrigerant that has exited the condenser 2 is decompressed. Moreover, the heat exchange amount of the supercooling heat exchanger 3 can be ensured reliably, and the supercooling degree of the supercooling heat exchanger 3 can be controlled reliably. In addition, since the refrigerant on the inlet side of the second electronic expansion valve 6 can be reliably used as a liquid refrigerant, the stability of the refrigeration cycle in the second electronic expansion valve 6 is improved, and the flow noise of the refrigerant is increased. In addition, there is no occurrence of abnormal vibrations and a highly reliable refrigeration air conditioner can be provided.

  Further, when the condensing pressure becomes equal to or higher than the second predetermined value (3.5 MPa), the control device 10 opens the second electronic expansion valve 6 and supplies the intermediate pressure gas-liquid two-phase refrigerant to the supercooling heat exchanger 3. Further, when the condensation pressure becomes 3.5 MPa or less, the second electronic expansion valve 6 is fully closed so that the intermediate-pressure gas-liquid two-phase refrigerant is not supplied to the supercooling heat exchanger 3. Therefore, the intermediate pressure gas-liquid two-phase refrigerant is supplied to the supercooling heat exchanger 3 only when the outlet water temperature of the condenser 2 is high and the condensation pressure needs to be kept low, and the outlet of the condenser 2 is in a high-pressure gas-liquid two-phase state. It can be.

  In the fourth embodiment, the second electronic expansion valve 6 is opened when the refrigerant pressure on the discharge side of the compressor 1 detected by the pressure sensor 11 is 3.5 MPa or more. However, the present invention is not limited to this. It is not something. For example, when the outlet water temperature of the condenser 2 is 50 ° C. or higher, the second electronic expansion valve 6 is opened, and when the outlet temperature is lower than 50 ° C., the second electronic expansion valve 6 is fully opened. It may be closed. Moreover, you may make it control opening / closing of the 2nd electronic expansion valve 6 with the set value of outlet water temperature instead of outlet water temperature.

Embodiment 5 FIG.
FIG. 5 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 5 of the present invention.
In FIG. 5, a refrigeration cycle device 31 of a refrigeration air conditioner is configured by sequentially connecting a compressor 1, a condenser 2, a first electronic expansion valve 4, which is a first decompression device, and an evaporator 5 through a refrigerant pipe. ing. Further, in the refrigeration cycle apparatus, the refrigerant (high pressure gas-liquid two-phase refrigerant) from the condenser 2 is heated between the condenser 2 and the first electronic expansion valve 4 and the low-temperature refrigerant (intermediate pressure gas-liquid two-phase refrigerant) and heat. A supercooling heat exchanger 3 that replaces and cools is provided. Further, a second electronic expansion valve is connected from the refrigerant pipe inserted between the first electronic expansion valve 4 and the supercooling heat exchanger 3 to the intermediate pressure chamber in the compressor 1 via the supercooling heat exchanger 3. A bypass pipe 7 for bypassing via 6 (second decompression device) is provided.

  The condenser 2 is composed of, for example, a plate heat exchanger, and heats water with a condensed refrigerant during heating, and supplies the water as, for example, high-temperature water of 60 ° C. The evaporator 5 is composed of, for example, a plate fin and tube heat exchanger, and exchanges heat with air. The supercooling heat exchanger 3 is configured to cool the high-pressure gas-liquid two-phase refrigerant from the condenser 2 with the intermediate-pressure gas-liquid two-phase refrigerant decompressed by the second electronic expansion valve 6. The intermediate-pressure gas-liquid two-phase refrigerant exiting the supercooling heat exchanger 3 is introduced into the intermediate pressure chamber in the compressor 1 through the bypass pipe 7.

  In addition to the pressure sensor 11, a thermistor 22 that detects the temperature of the high-pressure vapor refrigerant discharged from the compressor 1 is attached to the refrigerant pipe between the compressor 1 and the condenser 2. In the present embodiment, the thermistor 21 shown in FIG. 5 is the first thermistor 21 (first refrigerant temperature detecting means), and the thermistor 22 is the second thermistor 22 (second refrigerant temperature detecting means).

  In addition to controlling the opening degree of the first electronic expansion valve 4, the control device 10 according to the fifth embodiment determines the opening degree of the second electronic expansion valve 6 from the refrigerant pressure on the discharge side of the compressor 1 and the second thermistor. Control is performed based on the refrigerant temperature on the discharge side of the compressor 1 detected by the compressor 22.

Next, the operation of the fifth embodiment will be described.
The high-pressure vapor refrigerant compressed by the compressor 1 is condensed in the condenser 2 and flows into the supercooling heat exchanger 3 as a high-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is cooled by the intermediate-pressure gas-liquid two-phase refrigerant that has exited the second electronic expansion valve 6 in the supercooling heat exchanger 3, and becomes a high-pressure supercooled liquid state. It flows into the expansion valve 4. The high-pressure supercooled liquid refrigerant is depressurized in the first electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the evaporator 5, exchanges heat with air and evaporates, Become. The low-pressure vapor refrigerant is sucked into the compressor 1 and compressed again by the compressor 1.

  A part of the high-pressure supercooled liquid refrigerant exiting the supercooling heat exchanger 3 is decompressed to an intermediate pressure by the second electronic expansion valve 6 to become an intermediate-pressure gas-liquid two-phase refrigerant and the supercooling heat exchanger. 3 and exchanges heat with the high-pressure gas-liquid two-phase refrigerant from the condenser 2. The intermediate-pressure gas-liquid two-phase refrigerant that has passed through the supercooling heat exchanger 3 flows into the intermediate pressure chamber in the compressor 1 through the bypass pipe of the bypass circuit 32, and the low pressure from the evaporator 5 in the compressor 1. It merges with the vapor refrigerant and is compressed again by the compressor 1.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature in the supercooled liquid state on the outlet side of the supercooling heat exchanger 3 detected by the first thermistor 21 and calculates the difference between the previously calculated saturated liquid temperature and the refrigerant temperature. The degree of supercooling on the outlet side of the supercooling heat exchanger 3 is calculated. Then, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and when there is a difference from the first predetermined value, the degree of supercooling is 5 ° C. The opening degree of the first electronic expansion valve 4 is controlled. For example, when the calculated degree of supercooling is lower than 5 ° C., the control device 10 reduces the opening degree of the first electronic expansion valve 4 so that the degree of supercooling increases to 5 ° C., and the degree of supercooling is 5 When it is higher than ° C., the opening degree of the first electronic expansion valve 4 is increased so that the degree of supercooling is lowered to 5 ° C.

  Further, the control device 10 calculates a saturated vapor temperature from the pressure of the high-pressure vapor refrigerant read through the pressure sensor 11. Next, the control device 10 reads the refrigerant temperature on the discharge side of the compressor 1 detected by the second thermistor 22, and determines the refrigerant on the discharge side of the compressor 1 from the difference between the previously calculated saturated vapor temperature and the refrigerant temperature. Calculate the degree of superheat. Furthermore, the control device 10 compares the calculated refrigerant superheat degree with a third predetermined value, for example, 20 ° C., and if there is a difference between the third predetermined value, the refrigerant superheat degree is set to 20 ° C. The opening degree of the second electronic expansion valve 6 is controlled. For example, when the calculated refrigerant superheat degree is lower than 20 ° C., the control device 10 reduces the opening degree of the second electronic expansion valve 6 so that the refrigerant superheat degree is increased to 20 ° C., and the refrigerant superheat degree is 20 ° C. When it is higher than ° C., the opening degree of the second electronic expansion valve 6 is increased so that the refrigerant superheat degree is lowered to 20 ° C.

  As described above, according to the fifth embodiment, the intermediate pressure air in which the supercooling heat exchanger 3 is provided on the outlet side of the condenser 2 and a part of the refrigerant exiting the supercooling heat exchanger 3 is reduced to the intermediate pressure. The high-pressure gas-liquid two-phase refrigerant from the condenser 2 is cooled by the liquid two-phase refrigerant. Further, the opening degree of the first electronic expansion valve 4 is controlled so that the degree of supercooling on the outlet side of the supercooling heat exchanger 3 is always 5 ° C. As a result, the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the first electronic expansion valve 4 is in a supercooled liquid state under any operating condition or load condition. It can be. For this reason, even in a high-temperature hot water supply operation in which the outlet water temperature of the condenser 2 is 60 ° C., the refrigerant on the outlet side of the condenser 2 is in a high-pressure gas-liquid two-phase state, and the condenser 2 has excessive heat transfer characteristics. There is no coolant. Therefore, the condensing pressure can be lowered, the upper limit temperature can be increased with respect to the conventional upper limit of the outlet water temperature of 55 ° C., and the condensing pressure can be lowered, so that an efficient operation is possible.

  Further, since the opening degree of the first electronic expansion valve 4 is controlled by the control device 10 so that the degree of supercooling of the refrigerant on the outlet side of the supercooling heat exchanger 5 is always 5 ° C., the first electronic type The refrigerant passing through the expansion valve 4 can always maintain the state of the supercooled liquid even if the operation condition or load condition changes. Therefore, the stability of the refrigeration cycle is improved, and there is no generation of refrigerant flow noise or abnormal vibration, and a refrigeration air conditioner with low noise can be realized.

  Furthermore, since the opening degree of the second electronic expansion valve 6 is controlled by the control device 10 so that the refrigerant superheat degree on the discharge side of the compressor 1 is always 20 ° C., the refrigerant superheat on the discharge side of the compressor 1 is controlled. It is possible to reliably maintain the degree of refrigerant superheating on the discharge side of the compressor 1 at 20 ° C. during high-temperature hot water supply in which the temperature tends to rise. Therefore, the temperature rise of the lubricating oil of the compressor 1 or the compressor 1 can be suppressed, and a highly reliable refrigeration air conditioner can be provided.

Embodiment 6 FIG.
FIG. 6 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 6 of the present invention.
In FIG. 6, a refrigeration cycle device 31 of a refrigeration air conditioner includes a compressor 1, a four-way valve 8 for switching between a cooling operation and a heating operation, a first heat exchanger 2a, a first electronic expansion valve 4 (first decompression device), The second heat exchanger 5a and the accumulator 9 are sequentially connected by a refrigerant pipe. Further, in the refrigeration cycle apparatus, the refrigerant (high-pressure gas-liquid two-phase refrigerant) from the first heat exchanger 2a is used as the low-temperature refrigerant (intermediate pressure gas-liquid) between the first heat exchanger 2a and the first electronic expansion valve 4. A supercooling heat exchanger 3 is provided for heat exchange with the two-phase refrigerant) and cooling. Further, a second electronic expansion valve is connected from the refrigerant pipe inserted between the first electronic expansion valve 4 and the supercooling heat exchanger 3 to the intermediate pressure chamber in the compressor 1 via the supercooling heat exchanger 3. A bypass pipe 7 for bypassing via 6 (second decompression device) is provided.

  The 1st heat exchanger 2a consists of plate type heat exchangers, for example, heats inflowing water with a condensation refrigerant at the time of heating, and supplies it as hot water of 60 ° C, for example. The 2nd heat exchanger 5a consists of a plate fin and tube heat exchanger, for example, and heat-exchanges with air. The supercooling heat exchanger 3 is composed of, for example, a plate type heat exchanger, and the high pressure gas-liquid two-phase refrigerant from the first heat exchanger 2a is obtained by the intermediate-pressure gas-liquid two-phase refrigerant decompressed by the second electronic expansion valve 6. It is configured to cool. The intermediate-pressure gas-liquid two-phase refrigerant exiting the supercooling heat exchanger 3 is introduced into the intermediate pressure chamber in the compressor 1 through the bypass pipe 7.

  A first thermistor 21 (first refrigerant temperature detecting means) for detecting the refrigerant temperature on the outlet side of the supercooling heat exchanger 3 is attached to the refrigerant pipe on the outlet side of the supercooling heat exchanger 3. The refrigerant pipe between the compressor 1 and the four-way valve 7 is discharged from the compressor 1 and a pressure sensor 11 (refrigerant pressure detecting means) that detects a refrigerant pressure (pressure of high-pressure vapor refrigerant) on the discharge side of the compressor 1. A second thermistor 22 (second refrigerant temperature detecting means) for detecting the temperature of the high-pressure vapor refrigerant is attached. Furthermore, the refrigerant | coolant piping between the 1st heat exchanger 2a and the supercooling heat exchanger 3 is equipped with the 3rd thermistor 23 (3rd refrigerant | coolant temperature detection means) which detects the refrigerant | coolant temperature of the exit side of the 1st heat exchanger 2a. Is attached.

  The control device 10 according to the sixth embodiment is based on the refrigerant pressure on the discharge side of the compressor 1 detected by the pressure sensor 11 and the refrigerant temperature on the discharge side of the compressor 1 detected by the second thermistor 22. The opening degree of the electronic expansion valve 6 is controlled. Further, when the second electronic expansion valve 6 is open, the control device 10 adjusts the refrigerant pressure detected by the pressure sensor 11 and the refrigerant temperature on the outlet side of the supercooling heat exchanger 3 detected by the first thermistor 21. Based on this, the opening degree of the first electronic expansion valve 4 is controlled. Further, when the second electronic expansion valve 6 is closed, the control device 10 determines the refrigerant pressure detected by the pressure sensor 11 and the refrigerant temperature on the outlet side of the first heat exchanger 2a detected by the third thermistor 23. Based on this, the opening degree of the first electronic expansion valve 4 is controlled.

Next, the operation of the sixth embodiment will be described.
During the heating operation, the high-pressure vapor refrigerant compressed by the compressor 1 flows into the first heat exchanger 2a through the four-way valve 7, is condensed by the first heat exchanger 2a, and becomes a high-pressure gas-liquid two-phase refrigerant, It flows into the supercooling heat exchanger 3. The gas-liquid two-phase refrigerant is cooled by the intermediate-pressure gas-liquid two-phase refrigerant that has exited the second electronic expansion valve 6 in the supercooling heat exchanger 3, and becomes a high-pressure supercooled liquid state. It flows into the expansion valve 4. The high-pressure supercooled liquid refrigerant is depressurized in the first electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the second heat exchanger 5 a, exchanges heat with air, and evaporates. It becomes a vapor refrigerant. The low-pressure vapor refrigerant is sucked into the compressor 1 through the accumulator 9 and compressed again.

  A part of the high-pressure supercooled liquid refrigerant that has exited the supercooling heat exchanger 3 is decompressed to an intermediate pressure by the second electronic expansion valve 6 and becomes an intermediate-pressure gas-liquid two-phase refrigerant. To exchange heat with the high-pressure gas-liquid two-phase refrigerant from the first heat exchanger 2a. The intermediate-pressure gas-liquid two-phase refrigerant via the supercooling heat exchanger 3 flows into the intermediate pressure chamber in the compressor 1 through the bypass pipe 7 and merges with the low-pressure vapor refrigerant from the accumulator 9 in the compressor 1. Then, it is compressed again by the compressor 1.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature on the discharge side of the compressor 1 detected by the second thermistor 22, and determines the refrigerant on the discharge side of the compressor 1 from the difference between the previously calculated saturated vapor temperature and the refrigerant temperature. Calculate the degree of superheat. Then, the control device 10 compares the calculated refrigerant superheat degree with a third predetermined value, for example, 20 ° C., and when there is a difference between the third predetermined value, the refrigerant superheat degree is set to 20 ° C. The opening degree of the second electronic expansion valve 6 is controlled. For example, when the calculated refrigerant superheat degree is lower than 20 ° C., the control device 10 reduces the opening degree of the second electronic expansion valve 6 so that the refrigerant superheat degree is increased to 20 ° C., and the refrigerant superheat degree is 20 ° C. When it is higher than ° C., the opening degree of the second electronic expansion valve 6 is increased so that the refrigerant superheat degree is lowered to 20 ° C.

  Further, the control device 10 reads the refrigerant temperature in the supercooled liquid state on the outlet side of the supercooling heat exchanger 3 detected by the first thermistor 21 when the second electronic expansion valve 6 is open. The degree of supercooling on the outlet side of the supercooling heat exchanger 3 is calculated from the difference between the saturated liquid temperature calculated in step 1 and the refrigerant temperature. Next, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and when the degree of supercooling is lower than 5 ° C., the degree of supercooling is increased to 5 ° C. The opening degree of the first electronic expansion valve 4 is reduced. In addition, when the degree of supercooling is higher than 5 ° C., the control device 10 increases the opening degree of the first electronic expansion valve 4 so that the degree of supercooling decreases to 5 ° C.

  Further, the control device 10 reads the temperature of the high-pressure gas-liquid two-phase refrigerant on the outlet side of the first heat exchanger 2a detected by the third thermistor 23 when the second electronic expansion valve 6 is closed, The degree of supercooling on the outlet side of the first heat exchanger 2a is calculated from the difference between the previously calculated saturated liquid temperature and the refrigerant temperature. Next, the control device 10 compares the calculated degree of supercooling with the first predetermined value of 5 ° C., and when the degree of supercooling is lower than 5 ° C., the first electronic expansion valve is the same as described above. 4 is reduced. Further, when the degree of supercooling is higher than 5 ° C., the control device 10 increases the opening degree of the first electronic expansion valve 4 as described above.

  During the cooling operation, the first heat exchanger 2a operates as an evaporator and the second heat exchanger 5a operates as a condenser. However, the second electronic expansion valve 6 is always closed, and the supercooling heat exchanger is operated. 3 is controlled so as not to exchange heat.

  As described above, according to the sixth embodiment, the supercooling heat exchanger 3 is provided on the outlet side of the first heat exchanger 2a, and a part of the refrigerant exiting the supercooling heat exchanger 3 is reduced to an intermediate pressure. The high-pressure gas-liquid two-phase refrigerant from the first heat exchanger 2a is cooled by the intermediate-pressure gas-liquid two-phase refrigerant. Further, the opening degree of the first electronic expansion valve 4 is controlled so that the degree of supercooling on the outlet side of the supercooling heat exchanger 3 is always 5 ° C. As a result, the refrigerant on the outlet side of the first heat exchanger 2a is in a high-pressure gas-liquid two-phase state and the refrigerant on the inlet side of the first electronic expansion valve 4 is excessively passed under any operating condition or load condition. It can be in a cooling liquid state. For this reason, even in the high temperature hot water supply operation in which the outlet water temperature of the first heat exchanger 2a is 60 ° C., the refrigerant on the outlet side of the first heat exchanger 2a is in a high-pressure gas-liquid two-phase state, and the first heat exchanger 2a There is no supercooled liquid with poor heat transfer characteristics inside. Therefore, the condensing pressure can be lowered, the upper limit temperature can be increased with respect to the conventional upper limit of the outlet water temperature of 55 ° C., and the condensing pressure can be lowered, so that an efficient operation is possible.

  Moreover, the control object of the 1st electronic expansion valve 4 is changed with the opening / closing state of the 2nd electronic expansion valve 6, and the refrigerating cycle is always controlled to the optimal state. When the second electronic expansion valve 6 is fully closed and the intermediate-pressure gas-liquid two-phase refrigerant is not supplied to the supercooling heat exchanger 3, the high-pressure gas-liquid two-phase refrigerant exiting the first heat exchanger 2a is supercooling heat exchange. It passes through the vessel 3 without heat exchange. As a result, the pressure decreases by the amount of pressure loss due to passing through the supercooling heat exchanger 3. In order to accurately detect the degree of supercooling on the outlet side of the first heat exchanger 2a, it is preferable to use the refrigerant temperature on the outlet side of the first heat exchanger 2a. It is more appropriate than using temperature. As a result, it is possible to provide a highly reliable refrigeration air conditioner that can reliably control the refrigeration cycle to an optimum state, has high efficiency, and does not generate liquid back.

  In the sixth embodiment, the example in which the second electronic expansion valve 6 is controlled by the refrigerant superheat degree on the discharge side of the compressor 1 has been described, but the present invention is not limited to this. For example, it may be controlled by the refrigerant temperature on the discharge side of the compressor 1. That is, when the refrigerant temperature on the discharge side of the compressor 1 is 110 ° C. or lower, the second electronic expansion valve 6 is fully closed, and when the refrigerant temperature exceeds 110 ° C., the refrigerant temperature on the discharge side of the compressor 1 is The second electronic expansion valve 6 is controlled to be 110 ° C.

Embodiment 7 FIG.
FIG. 7 is a configuration diagram of a refrigerant circuit showing a refrigerating and air-conditioning apparatus according to Embodiment 7 of the present invention.
In FIG. 7, the refrigeration / air conditioning apparatus of the seventh embodiment includes the same refrigeration cycle apparatus 31 as that of the sixth embodiment shown in FIG. 6, and the first and third thermistors 21 and 23 are removed. . The controller 10 detects the refrigerant pressure on the discharge side of the compressor 1 detected by the pressure sensor 11 (refrigerant pressure detection means) and the refrigerant temperature on the discharge side of the compressor 1 detected by the thermistor 22 (refrigerant temperature detection means). Based on this, the opening degree of the first electronic expansion valve 4 and the second electronic expansion valve 6 is controlled.

Next, the operation of the seventh embodiment will be described.
During the heating operation, the high-pressure vapor refrigerant compressed by the compressor 1 flows into the first heat exchanger 2a through the four-way valve 8, and is condensed by the first heat exchanger 2a to become a high-pressure gas-liquid two-phase refrigerant. Then, it flows into the supercooling heat exchanger 3. The gas-liquid two-phase refrigerant is cooled by the intermediate-pressure gas-liquid two-phase refrigerant that has exited the second electronic expansion valve 6 in the supercooling heat exchanger 3, and becomes a high-pressure supercooled liquid state. It flows into the expansion valve 4. The high-pressure supercooled liquid refrigerant is depressurized in the first electronic expansion valve 4, becomes a low-pressure gas-liquid two-phase refrigerant, flows into the second heat exchanger 5 a, exchanges heat with air, and evaporates. It becomes a vapor refrigerant. The low-pressure vapor refrigerant is sucked into the compressor 1 through the accumulator 9 and compressed again.

  A part of the high-pressure supercooled liquid refrigerant exiting the supercooling heat exchanger 3 is decompressed to an intermediate pressure by the second electronic expansion valve 6 to become an intermediate-pressure gas-liquid two-phase refrigerant and the supercooling heat exchanger. 3 and exchanges heat with the high-pressure gas-liquid two-phase refrigerant from the first heat exchanger 2a. The intermediate-pressure gas-liquid two-phase refrigerant via the supercooling heat exchanger 3 flows into the intermediate pressure chamber in the compressor 1 through the bypass pipe 7 and merges with the low-pressure vapor refrigerant from the accumulator 9 in the compressor 1. Then, it is compressed again by the compressor 1.

  On the other hand, the control device 10 reads the pressure of the high-pressure vapor refrigerant on the discharge side of the compressor 1 detected by the pressure sensor 11 and calculates the saturated liquid temperature. Further, the control device 10 reads the refrigerant temperature on the discharge side of the compressor 1 detected by the thermistor 22, and determines the refrigerant superheat degree on the discharge side of the compressor 1 from the difference between the saturated vapor temperature calculated earlier and the refrigerant temperature. Is calculated. Then, the control device 10 compares the calculated refrigerant superheat degree with a third predetermined value, for example, 20 ° C., and when there is a difference between the third predetermined value, the refrigerant superheat degree is set to 20 ° C. The opening degree of the second electronic expansion valve 6 is controlled. For example, when the calculated refrigerant superheat degree is lower than 20 ° C., the control device 10 reduces the opening degree of the second electronic expansion valve 6 so that the refrigerant superheat degree is increased to 20 ° C., and the refrigerant superheat degree is 20 ° C. When it is higher than ° C., the opening degree of the second electronic expansion valve 6 is increased so that the refrigerant superheat degree is lowered to 20 ° C.

  Further, the control device 10 controls the first electronic expansion valve 4 so that the temperature difference between the previously calculated saturated liquid temperature and the outlet water temperature of the first heat exchanger 2a is a fourth predetermined value, for example, 3 ° C. To control the opening degree. For example, when the temperature difference is lower than 3 ° C., the control device 10 reduces the opening of the first electronic expansion valve 4 so that the temperature difference becomes 3 ° C., and the pressure on the discharge side of the compressor 1 To go up. On the contrary, when the temperature difference between the saturated liquid temperature and the outlet water temperature of the first heat exchanger 2a is higher than 3 ° C., the control device 10 controls the first electronic expansion valve so that the temperature difference becomes 3 ° C. 4 is increased, and the pressure on the discharge side of the compressor 1 is decreased.

  In the refrigerating and air-conditioning apparatus according to the seventh embodiment, the opening degree of the first electronic expansion valve 4 and the second electronic expansion valve 6 is controlled by two sensors, the pressure sensor 11 and the thermistor 22, and the above-described embodiment. Compared to 6, the number of sensors can be reduced, and the cost of the refrigeration air conditioner can be reduced.

DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 2a 1st heat exchanger, 3 Supercooling heat exchanger, 4 Electronic expansion valve (1st electronic expansion valve), 5 Evaporator, 5a 2nd heat exchanger, 6 2nd Electronic expansion valve,
7 bypass piping, 8 four-way valve, 9 accumulator, 10 control device, 11 pressure sensor, 21 thermistor (first thermistor), 22 second thermistor (thermistor),
23 3rd thermistor, 31 refrigeration cycle apparatus.

Claims (8)

A refrigeration cycle apparatus in which a compressor, a condenser, a first decompressor, and an evaporator are sequentially connected by a refrigerant pipe;
A supercooling heat exchanger that is inserted between the condenser of the refrigeration cycle apparatus and the first decompression apparatus and cools the refrigerant from the condenser by exchanging heat with a low-temperature refrigerant;
Refrigerant pressure detection means for detecting the pressure of the refrigerant discharged from the compressor;
First refrigerant temperature detection means for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger;
Based on the refrigerant pressure detected by the refrigerant pressure detection means and the refrigerant temperature detected by the first refrigerant temperature detection means, the degree of supercooling of the supercooling heat exchanger is calculated, and the degree of subcooling is calculated. A refrigerating and air-conditioning apparatus comprising: a control device that controls an opening of the first pressure reducing device so as to be a first predetermined value.   The refrigerating and air-conditioning apparatus according to claim 1, wherein a low-pressure gas-liquid two-phase refrigerant between the first decompression device and the evaporator is used as the low-temperature refrigerant of the supercooling heat exchanger.   The refrigerating and air-conditioning apparatus according to claim 1, wherein a low-pressure vapor refrigerant between the evaporator and the compressor is used as the low-temperature refrigerant of the supercooling heat exchanger. A bypass pipe bypassing from the refrigerant pipe inserted between the supercooling heat exchanger and the first pressure reducing device to the suction side of the compressor via the second pressure reducing device via the supercooling heat exchanger Provided,
The refrigerating and air-conditioning apparatus according to claim 1, wherein a low-pressure gas-liquid two-phase refrigerant flowing out of the second decompression device is used as the low-temperature refrigerant of the supercooling heat exchanger. Bypass piping bypassing from the refrigerant piping inserted between the supercooling heat exchanger and the first decompression device to the intermediate pressure chamber in the compressor via the second decompression device via the supercooling heat exchanger Provided,
The control device calculates the degree of supercooling of the supercooling heat exchanger based on the refrigerant pressure detected by the refrigerant pressure detecting means and the refrigerant temperature detected by the first refrigerant temperature detecting means, The opening degree of the first pressure reducing device is controlled so that the degree of supercooling becomes a first predetermined value, and the refrigerant pressure detected by the refrigerant pressure detecting means is compared with a second predetermined value. 2. The refrigeration according to claim 1, wherein when the pressure of the refrigerant is equal to or higher than a second predetermined value, the second pressure reducing device is opened, and the intermediate pressure refrigerant flows into the supercooling heat exchanger as a low-temperature refrigerant. Air conditioner. A refrigeration cycle apparatus in which a compressor, a condenser, a first decompressor, and an evaporator are sequentially connected by a refrigerant pipe;
A subcooling heat exchanger that is inserted between the condenser of the refrigeration cycle apparatus and the first decompression apparatus and cools the refrigerant from the condenser by exchanging heat with a low-temperature refrigerant;
Bypass piping bypassing from the refrigerant piping inserted between the supercooling heat exchanger and the first decompression device to the intermediate pressure chamber in the compressor via the second decompression device via the supercooling heat exchanger When,
Refrigerant pressure detection means for detecting the pressure of the refrigerant discharged from the compressor;
First refrigerant temperature detection means for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger;
Second refrigerant temperature detection means for detecting the temperature of the refrigerant on the discharge side of the compressor;
Based on the refrigerant pressure detected by the refrigerant pressure detection means and the refrigerant temperature detected by the first refrigerant temperature detection means, the degree of supercooling of the supercooling heat exchanger is calculated, and the degree of subcooling is calculated. The opening of the first pressure reducing device is controlled so as to be a first predetermined value, and the refrigerant pressure detected by the refrigerant pressure detecting means and the refrigerant temperature detected by the second refrigerant temperature detecting means. And a control device for controlling the degree of opening of the second pressure reducing device so that the refrigerant superheat degree is equal to or higher than a third predetermined value.
A refrigerating and air-conditioning apparatus, wherein an intermediate pressure refrigerant flows into the supercooling heat exchanger as a low-temperature refrigerant. A refrigeration cycle apparatus in which a compressor, a four-way valve, a first heat exchanger, a first pressure reducing device, and a second heat exchanger are sequentially connected by refrigerant piping;
A supercooling heat exchanger that is inserted between the first heat exchanger and the first decompression device of the refrigeration cycle apparatus and cools the refrigerant from the first heat exchanger by exchanging heat with a low-temperature refrigerant;
Bypass piping bypassing from the refrigerant piping inserted between the supercooling heat exchanger and the first decompression device to the intermediate pressure chamber in the compressor via the second decompression device via the supercooling heat exchanger When,
Refrigerant pressure detection means for detecting the pressure of the refrigerant on the discharge side of the compressor;
First refrigerant temperature detection means for detecting the temperature of the refrigerant on the outflow side of the supercooling heat exchanger;
Second refrigerant temperature detection means for detecting the temperature of the refrigerant on the discharge side of the compressor;
Third refrigerant temperature detection means for detecting the temperature of the refrigerant on the outflow side of the first heat exchanger;
Based on the refrigerant pressure detected by the refrigerant pressure detection means and the refrigerant temperature detected by the second refrigerant temperature detection means, the refrigerant superheat degree of the compressor is calculated, and the refrigerant superheat degree is the third Based on the refrigerant pressure detected by the refrigerant pressure detecting means and the refrigerant temperature detected by the first refrigerant temperature detecting means, the opening degree of the second pressure reducing device is controlled to be a predetermined value. A control device for calculating the degree of supercooling of the supercooling heat exchanger and controlling the opening of the first pressure reducing device so that the degree of supercooling becomes a first predetermined value,
When the second pressure reducing device is closed, the control device is configured to control the first pressure based on the refrigerant pressure detected by the refrigerant pressure detection unit and the refrigerant temperature detected by the third refrigerant temperature detection unit. Calculating the degree of supercooling of one heat exchanger, and controlling the opening of the first pressure reducing device so that the degree of supercooling becomes a first predetermined value;
A refrigerating and air-conditioning apparatus, wherein an intermediate pressure refrigerant flows into the supercooling heat exchanger as a low-temperature refrigerant. A refrigeration cycle apparatus in which a compressor, a four-way valve, a first heat exchanger, a first pressure reducing device, and a second heat exchanger are sequentially connected by refrigerant piping;
A supercooling heat exchanger that is inserted between the first heat exchanger and the first decompression device of the refrigeration cycle apparatus and cools the refrigerant from the first heat exchanger by exchanging heat with a low-temperature refrigerant;
Bypass piping bypassing from the refrigerant piping inserted between the supercooling heat exchanger and the first decompression device to the intermediate pressure chamber in the compressor via the second decompression device via the supercooling heat exchanger When,
Refrigerant pressure detection means for detecting the pressure of the refrigerant on the discharge side of the compressor;
Refrigerant temperature detection means for detecting the temperature of the refrigerant on the discharge side of the compressor;
The saturation vapor temperature is calculated from the refrigerant pressure detected by the refrigerant pressure detection means, the opening of the first decompression device is controlled so that the saturation vapor temperature becomes a fourth predetermined value, and the refrigerant The refrigerant superheat degree of the compressor is calculated based on the refrigerant pressure detected by the pressure detection means and the refrigerant temperature detected by the refrigerant temperature detection means, and the refrigerant superheat degree becomes a third predetermined value. And a control device for controlling the opening of the second pressure reducing device,
A refrigerating and air-conditioning apparatus, wherein an intermediate pressure refrigerant flows into the supercooling heat exchanger as a low-temperature refrigerant.

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