AIR CONDITIONING SYSTEM AND VENTILATION APPARATUS

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of International Application No. PCT/JP2024/009536 filed on Mar. 12, 2024, which is based on and claims priority to Japanese Patent Application No. 2023-038457 filed on Mar. 13, 2023. The contents of these applications are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to an air conditioning system and a ventilation apparatus.

BACKGROUND ART

Patent Document 1 discloses an exhaust heat recovery device that recovers exhaust heat when the inside air in a building is discharged and uses the recovered exhaust heat to warm the outside air supplied to the building. Patent Document 1 discloses that the heat exchanger on the exhaust side and the heat exchanger on the air supply side have closed circuits (refrigerant circuits) formed by a pipe connecting one end of the heat exchanger to a compressor and a pipe connecting the other end of the heat exchanger to an expansion valve, and a refrigerant is enclosed in the closed circuits.

CITATION LIST

Patent Document

• • Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-144401

SUMMARY

The present disclosure provides an air conditioning system including:

• • a first compressor;
  • a first heat exchanger provided outside a building and configured to perform heat exchange with outside air outside the building;
  • a second heat exchanger provided in a first path through which the outside air is supplied inside the building;
  • a first refrigerant circuit in which a first refrigerant flows, the first refrigerant circuit including the first compressor, the first heat exchanger, and the second heat exchanger being connected by a first refrigerant pipe;
  • a second compressor;
  • a third heat exchanger provided inside the building and configured to perform heat exchange with inside air inside the building;
  • a fourth heat exchanger provided in a second path through which the inside air is exhausted outside the building;
  • a second refrigerant circuit in which a second refrigerant flows, the second refrigerant circuit including the second compressor, the third heat exchanger, and the fourth heat exchanger being connected by a second refrigerant pipe; and
  • a first intermediate heat exchanger configured to perform heat exchange between the first refrigerant and the second refrigerant.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the schematic configuration of an air conditioning system according to a first embodiment;

FIG. 2 is a diagram explaining a refrigerant circuit in an air conditioning system according to the first embodiment;

FIG. 3 is a diagram explaining a refrigeration cycle during cooling by an air conditioning system according to the first embodiment;

FIG. 4 is a diagram explaining a refrigeration cycle during heating by an air conditioning system according to the first embodiment;

FIG. 5 is a diagram illustrating a schematic configuration of an air conditioning system according to a second embodiment;

FIG. 6 is a diagram explaining a refrigerant circuit in an air conditioning system according to the second embodiment;

FIG. 7 is a diagram for explaining a refrigeration cycle during cooling by an air conditioning system according to the second embodiment;

FIG. 8 is a diagram for explaining a refrigeration cycle during heating by an air conditioning system according to the second embodiment;

FIG. 9 is a diagram illustrating a schematic configuration of a ventilation apparatus according to a third embodiment;

FIG. 10 is a diagram explaining a refrigerant circuit in a ventilation apparatus according to the third embodiment;

FIG. 11 is a diagram explaining a refrigeration cycle during cooling by a ventilation apparatus according to the third embodiment;

FIG. 12 is a diagram explaining a refrigeration cycle during heating by a ventilation apparatus according to the third embodiment;

FIG. 13 is a diagram illustrating a schematic configuration of a ventilation apparatus according to a fourth embodiment;

FIG. 14 is a diagram explaining a refrigerant circuit in a ventilation apparatus according to the fourth embodiment;

FIG. 15 is a diagram explaining a refrigeration cycle during cooling by a ventilation apparatus according to the fourth embodiment;

FIG. 16 is a diagram explaining a refrigeration cycle during heating by a ventilation apparatus according to the fourth embodiment;

FIG. 17 is a diagram illustrating a schematic configuration of an air conditioning system according a fifth embodiment;

FIG. 18 is a diagram explaining a refrigerant circuit in an air conditioning system according to the fifth embodiment;

FIG. 19 is a diagram explaining a refrigeration cycle during cooling by an air conditioning system according to the fifth embodiment; and

FIG. 20 is a diagram explaining a refrigeration cycle during heating by an air conditioning system according to the fifth embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments will be described below with reference to the attached drawings. In the descriptions in the specification and drawings of each embodiment, components having substantially the same or corresponding functional configuration may be denoted by the same reference numerals, thereby omitting duplicate descriptions. Further, for ease of understanding, the scale of each part in the drawings may differ from the actual scale.

<<Air Conditioning System 1 According to a First Embodiment>>

An air conditioning system 1 according to the first embodiment will be described below. FIG. 1 is a diagram illustrating a schematic configuration of the air conditioning system 1 according to the first embodiment. FIG. 2 is a diagram explaining a primary-side refrigerant circuit CIR1 and a secondary-side refrigerant circuit CIR2 in the air conditioning system 1 according to the first embodiment. The air conditioning system 1 provides ventilation between the inside IDS and the outside OPS of a building BLD. The air conditioning system 1 provides air conditioning in the inside IDS of the building BLD.

The air taken in from the outside OPS of the building BLD by the air supply unit 20 is referred to as outside air OA. The air in the outside OPS of the building BLD is referred to as outside air OA in some cases. The air supplied to the inside IDS of the building BLD by the air supply unit 20 is referred to as supply air SA. The air taken in by the exhaust unit 40 from the inside IDS of the building BLD is referred to as return air RA. The air discharged by the exhaust unit 40 to the outside OPS of the building BLD is referred to as exhaust air EA.

<Configuration of the Air Conditioning System 1>

The air conditioning system 1 includes an outdoor unit 10, an air supply unit 20, an indoor unit 30, an exhaust unit 40, and a heat exchange unit 50. The air conditioning system 1 also includes a compressor 61, a compressor 62, an expansion valve 71, and an expansion valve 72.

[Outdoor Unit 10]

The outdoor unit 10 is provided in the outside OPS of the building BLD. The outdoor unit 10 is what is referred to as an outdoor unit. The outdoor unit 10 exchanges heat between the outside air OA in the outside OPS of the building BLD and the primary-side refrigerant REF1. The outdoor unit 10 includes an outdoor heat exchanger 11 and a fan 22.

The outdoor heat exchanger 11 exchanges heat between the outside air OA and the primary-side refrigerant REF1 in the outside OPS of the building BLD. The outdoor heat exchanger 11 includes a plurality of plate-type fins and a pipe that penetrate the fins and through which the primary-side refrigerant REF1 flows. By passing the outside air OA between the plurality of plate-type fins, the outdoor heat exchanger 11 exchanges heat between the outside air OA and the primary-side refrigerant REF1.

The fan 12 passes the outside air OA through the outdoor heat exchanger 11. The fan 12 may, for example, supply the outside air OA to the outdoor heat exchanger 11 or exhaust the outside air OA that has passed through the outdoor heat exchanger 11. The outside air OA that has been passed through the outdoor heat exchanger 11 by the fan 12 exchanges heat with the primary-side refrigerant REF1 flowing through the outdoor heat exchanger 11. The outside air OA that has exchanged heat with the outdoor heat exchanger 11 is exhausted to the outside OPS of the building BLD. The fan 12 is, for example, an axial flow fan.

[Air Supply Unit 20]

The air supply unit 20 takes in the outside air OA from the outside OPS of the building BLD, and exchanges heat between the captured outside air OA and the primary-side refrigerant REF1. The air supply unit 20 then supplies the outside air OA that has undergone heat exchange to the inside IDS of the building BLD as supply air SA. The air supply unit 20 includes an air supply heat exchanger 21 and the fan 22. A path in which the outside air OA, which is the air of the outside OPS of the building BLD, is supplied to the inside IDS of the building BLD as the supply air SA via the air supply unit 20, is referred to as an air supply path P1.

The air supply heat exchanger 21 performs heat exchange between the outside air OA and the primary-side refrigerant REF1. The air supply heat exchanger 21 is provided with a plurality of plate-shaped fins and a pipe that penetrates the fins and through which the primary-side refrigerant REF1 flows.

In the air supply heat exchanger 21, the primary-side refrigerant REF1 flows through the pipe of the air supply heat exchanger 21. When the outside air OA flows between the fins of the air supply heat exchanger 21, heat exchange is performed between the outside air OA and the primary-side refrigerant REF1 flowing through the pipe of the air supply heat exchanger 21.

The fan 22 blows the outside air OA to the air supply heat exchanger 21. The outside air OA blown to the air supply heat exchanger 21 by the fan 22 exchanges heat with the primary-side refrigerant REF1 flowing through the air supply heat exchanger 21. The outside air OA that has undergone heat exchange is blown inside the building BLD as the supply air SA. The fan 22 is, for example, a centrifugal fan or an axial flow fan.

With respect to the arrangement of the air supply heat exchanger 21 and the fan 22, the arrangement may be reversed, and the outside air OA that has undergone heat exchange by the air supply heat exchanger 21 may be blown indoors by the fan 22.

[Indoor Unit 30]

The indoor unit 30 is provided in the inside IDS of the building BLD. The indoor unit 30 is what is referred to as an indoor unit. The indoor unit 30 exchanges heat between the air of the inside IDS of the building BLD and the secondary-side refrigerant REF2. The indoor unit 30 includes an indoor heat exchanger 31.

The indoor heat exchanger 31 exchanges heat between the air of the inside IDS of the building BLD and the secondary-side refrigerant REF2. The indoor heat exchanger 31 includes a plurality of plate-shaped fins and a pipe that penetrate the fins and through which the secondary-side refrigerant REF2 flows. The indoor heat exchanger 31 exchanges heat between the inside IDS air and the secondary-side refrigerant REF2 by passing the inside IDS air between the plurality of plate type fins.

The indoor unit 30 may be provided with a fan. The inside IDS air may be sent to the indoor heat exchanger 31 by the fan provided in the indoor unit 30, or the inside IDS air passed through the indoor heat exchanger 31 may be exhausted to the inside IDS.

[Exhaust Unit 40]

The exhaust unit 40 takes in the return air RA from the inside IDS of the building BLD, performs heat exchange between the captured return air RA and the secondary-side refrigerant REF2, and exhausts the returned air RA after heat exchange to the outside OPS of the building BLD as exhaust air EA. The exhaust unit 40 includes an exhaust heat exchanger 41 and the fan 42. A path in which the return air RA, which is the air of the inside IDS of the building BLD, is exhausted to the outside OPS of the building BLD as exhaust air EA via the exhaust unit 40, is referred to as an exhaust path P2.

The exhaust heat exchanger 41 exchanges heat between the return air RA and the secondary-side refrigerant REF2. The exhaust heat exchanger 41 includes a plurality of plate-shaped fins and a pipe that penetrate the fins and through which refrigerant flows. As the return air RA flows between the fins of the exhaust heat exchanger 41, heat exchange is performed between the return air RA and the secondary-side refrigerant REF2 flowing in the pipe of the exhaust heat exchanger 41.

The fan 42 blows the return air RA to the exhaust heat exchanger 41. The fan 42 is, for example, a centrifugal fan or an axial flow fan. The return air RA heat exchanged by the exhaust heat exchanger 41 is discharged outdoors as exhaust air EA.

The arrangement of the exhaust heat exchanger 41 and the fan 42 may be reversed, and the return air RA heat exchanged by the exhaust heat exchanger 41 may be blown outdoors of the building BLD as exhaust air EA by the fan 42.

[Heat Exchange Unit 50]

The heat exchange unit 50 exchanges heat between the primary-side refrigerant REF1 and the secondary-side refrigerant REF2. The heat exchange unit 50 includes an intermediate heat exchanger 51. The intermediate heat exchanger 51 is what is referred to as a cascade heat exchanger. The intermediate heat exchanger 51 exchanges heat between the primary-side refrigerant REF1 and the secondary-side refrigerant REF2.

[Compressor 61 and Compressor 62]

The compressor 61 discharges the compressed primary-side refrigerant REF1. The compressor 62 discharges the compressed secondary-side refrigerant REF2. Each of the compressor 61 and compressor 62 is what is referred to as a compressor. Each of the compressor 61 and the compressor 62 is, for example, a turbo compressor or a positive displacement compressor. Each of the compressor 61 and the compressor 62 can change the direction in which the refrigerant is discharged by providing a selector valve or the like.

[Expansion Valve 71 and Expansion Valve 72]

The expansion valve 71 depressurizes the compressed primary-side refrigerant REF1. The expansion valve 72 depressurizes the compressed secondary-side refrigerant REF2.

<Primary-Side Refrigerant Circuit CIR1 and Secondary-Side Refrigerant Circuit CIR2>

The primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR2 in the air conditioning system 1 will be described below. FIG. 2 is a diagram for explaining the primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR2 in the air conditioning system 1 according to the first embodiment. In FIG. 2, the arrows of the primary-side refrigerant REF1 and the secondary-side refrigerant REF2 indicate the direction in which the refrigerant flows during cooling.

The air conditioning system 1 includes the primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR2. The primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR2 are thermally connected via the intermediate heat exchanger 51.

[Primary-Side Refrigerant Circuit CIR1]

The primary-side refrigerant circuit CIR1 includes the compressor 61, the outdoor heat exchanger 11, the air supply heat exchanger 21, the intermediate heat exchanger 51, and the expansion valve 71 connected via a primary-side refrigerant pipe 81. Through the primary-side refrigerant circuit CIR1, a primary-side refrigerant REF1 flows therein via the primary-side refrigerant pipe 81. The primary-side refrigerant circuit CIR1 constitutes a primary-side refrigeration cycle HC1 described below.

In the primary-side refrigerant circuit CIR1, the outdoor heat exchanger 11, the expansion valve 71, the intermediate heat exchanger 51, and the air supply heat exchanger 21 are connected in this order from the compressor 61, returning to the compressor 61.

During cooling, in the primary-side refrigerant circuit CIR1, the primary-side refrigerant REF1 compressed and heated by the compressor 61 flows in order from the compressor 61 to the outdoor heat exchanger 11 and the expansion valve 71. The primary-side refrigerant REF1 is depressurized at the expansion valve 71. The depressurized primary-side refrigerant REF1 flows in order from the expansion valve 71 to the intermediate heat exchanger 51 and the air supply heat exchanger 21. The primary-side refrigerant REF1 that has passed through the air supply heat exchanger 21 returns to the compressor 61.

During heating, in the primary-side refrigerant circuit CIR1, the primary-side refrigerant REF1 that has been compressed and heated by the compressor 61 flows in order from the compressor 61 to the air supply heat exchanger 21, the intermediate heat exchanger 51, and the expansion valve 71. The primary-side refrigerant REF1 is depressurized at the expansion valve 71. The depressurized primary-side refrigerant REF1 flows from the expansion valve 71 to the outdoor heat exchanger 11. The primary-side refrigerant REF1 that has passed through the outdoor heat exchanger 11 returns to the compressor 61.

[Secondary-Side Refrigerant Circuit CIR2]

The secondary-side refrigerant circuit CIR2 includes the compressor 62, the indoor heat exchanger 31, the exhaust heat exchanger 41, the intermediate heat exchanger 51, and the expansion valve 72 connected by a secondary-side refrigerant pipe 82. In the secondary-side refrigerant circuit CIR2, a secondary-side refrigerant REF2 flows therein via the secondary-side refrigerant pipe 82. The secondary-side refrigerant circuit CIR2 constitutes a secondary-side refrigeration cycle HC2, which will be described below.

In the secondary-side refrigerant circuit CIR2, the intermediate heat exchanger 51, the exhaust heat exchanger 41, the expansion valve 72, and the indoor heat exchanger 31 are connected in this order from the compressor 62, returning to the compressor 62.

During cooling, in the secondary-side refrigerant circuit CIR2, the secondary-side refrigerant REF2 compressed and heated by the compressor 62 flows in order from the compressor 62 to the intermediate heat exchanger 51, the exhaust heat exchanger 41, and the expansion valve 72. The secondary-side refrigerant REF2 is depressurized at the expansion valve 72. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 72 to the indoor heat exchanger 31. The secondary-side refrigerant REF2 that has passed through the indoor heat exchanger 31 returns to the compressor 62.

During heating, in the secondary-side refrigerant circuit CIR2, the secondary-side refrigerant REF2 that has been compressed and heated by the compressor 62 flows from the compressor 62 to the indoor heat exchanger 31 and the expansion valve 72 in this order. The secondary-side refrigerant REF2 is depressurized at the expansion valve 72. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 72 to the exhaust heat exchanger 41 and the intermediate heat exchanger 51. The secondary-side refrigerant REF2 that has passed through the intermediate heat exchanger 51 returns to the compressor 62.

<Primary-Side Refrigeration Cycle HC1 and Secondary-Side Refrigeration Cycle HC2>

The primary-side refrigeration cycle HC1 in the primary-side refrigerant circuit CIR1 and the secondary-side refrigeration cycle HC2 in the secondary-side refrigerant circuit CIR2 will be described below. FIG. 3 is a diagram for explaining the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC2 during cooling by the air conditioning system 1 according to the first embodiment. FIG. 4 is a diagram for explaining the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC2 during heating by the air conditioning system 1 according to the first embodiment.

FIGS. 3 and 4 are diagrams schematically illustrating the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC2 in an enthalpy-pressure diagram (Mollier diagram). FIGS. 3 and 4 are diagrams for explaining the operation, and the refrigeration cycle is simplified. The horizontal axes of FIGS. 3 and 4 respectively indicate enthalpy. The vertical axes of FIGS. 3 and 4 respectively indicate pressure.

First, the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC2 of the air conditioning system 1 according to the first embodiment during cooling will be described with reference to FIG. 3.

First, the primary-side refrigeration cycle HC1 will be described in order from point A1, which indicates the position in the compressor 61 at which the primary-side refrigerant REF1 is taken in.

During cooling, when the compressor 61 compresses the primary-side refrigerant REF1, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 3, when the compressor 61 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2. Specifically, at points A1 to A2, the temperature of the primary-side refrigerant REF1 increases, the enthalpy increases, and the pressure increases.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 3, when the primary-side refrigerant REF1 is cooled in the outdoor heat exchanger 11, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3, as indicated in the section HX1. Specifically, at points A2 to A3, the pressure is constant, the temperature of the primary-side refrigerant REF1 decreases, and the enthalpy decreases.

Next, the pressure of the primary-side refrigerant REF1 is reduced by being depressurized at the expansion valve 71. Therefore, in FIG. 3, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4 when the primary-side refrigerant REF1 is depressurized at the expansion valve 71. Specifically, from point A3 to point A4, the enthalpy of the primary-side refrigerant REF1 remains constant and the pressure decreases.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with the heated secondary-side refrigerant REF2 in the intermediate heat exchanger 51. The primary-side refrigerant REF1 is heated by exchanging heat with the outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 3, when the primary-side refrigerant REF1 is heated in the intermediate heat exchanger 51 and the air supply heat exchanger 21, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1. Specifically, from point A4 to point A1, the pressure is constant, and the temperature of the primary-side refrigerant REF1 rises, and the enthalpy increases. In FIG. 3, the section HX5 indicates the section heated by the intermediate heat exchanger 51, and the section HX2 indicates the section heated by the air supply heat exchanger 21.

Next, the secondary-side refrigeration cycle HC2 will be described in order starting from point B1, which indicates the position in the compressor 62 at which the secondary-side refrigerant REF2 is taken in.

During cooling, when the compressor 62 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature of the secondary-side refrigerant REF2 also increases. Therefore, in FIG. 3, when the compressor 62 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2. Specifically, from point B1 to point B2, the temperature of the secondary-side refrigerant REF2 increases, the enthalpy increases, and the pressure increases.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the cooled primary-side refrigerant REF1 in the intermediate heat exchanger 51. The secondary-side refrigerant REF2 is cooled by exchanging heat with the return air RA in the exhaust heat exchanger 41. Therefore, in FIG. 3, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to B3 as the secondary-side refrigerant REF2 is cooled in the intermediate heat exchanger 51 and the exhaust heat exchanger 41. Specifically, from point B2 to point B3, the pressure is constant, and the temperature of the secondary-side refrigerant REF2 decreases, and the enthalpy decreases. In FIG. 3, the section HX5 indicates the section cooled by the intermediate heat exchanger 51, and the section HX4 indicates the section cooled by the exhaust heat exchanger 41.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valve 72. Therefore, in FIG. 3, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 72, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4. Specifically, from point B3 to point B4, the enthalpy of the secondary-side refrigerant REF2 remains constant and the pressure decreases.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with inside IDS air in the indoor heat exchanger 31. Therefore, in FIG. 3, when the secondary-side refrigerant REF2 is heated in the indoor heat exchanger 31, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1 as indicated in the section HX3. Specifically, from point B4 to point B1, the pressure remains constant and the temperature of the secondary-side refrigerant REF2 increases and the enthalpy increases.

Next, the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC2 of the air conditioning system 1 according to the first embodiment during heating will be described with reference to FIG. 4.

First, the primary-side refrigeration cycle HC1 will be described in order from point A1, which indicates the position in the compressor 61 at which the primary-side refrigerant REF1 is taken in.

When the compressor 61 compresses the primary-side refrigerant REF1 during heating, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 3, when the compressor 61 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2. Specifically, from point A1 to point A2, the temperature of the primary-side refrigerant REF1 increases, the enthalpy increases, and the pressure increases.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with the cooled secondary-side refrigerant REF2 in the intermediate heat exchanger 51. The primary-side refrigerant REF1 is cooled by exchanging heat with outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 4, when the primary-side refrigerant REF1 is cooled in the intermediate heat exchanger 51 and the air supply heat exchanger 21, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3. Specifically, from point A2 to point A3, the pressure is constant, and the temperature of the primary-side refrigerant REF1 decreases and the enthalpy decreases. In FIG. 4, the section HX5 indicates the section cooled by the intermediate heat exchanger 51, and the section HX2 indicates the section cooled by the air supply heat exchanger 21.

Next, the pressure of the primary-side refrigerant REF1 decreases by being depressurized at the expansion valve 71. Therefore, in FIG. 4, when the primary-side refrigerant REF1 is depressurized at the expansion valve 71, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4. Specifically, from point A3 to point A4, the enthalpy of the primary-side refrigerant REF1 remains constant and the pressure decreases.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 4, when the primary-side refrigerant REF1 is heated in the outdoor heat exchanger 11, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1 as indicated in the section HX1. Specifically, from point A4 to point A1, the pressure is constant, and the temperature of the primary-side refrigerant REF1 rises and the enthalpy increases.

Next, the secondary-side refrigeration cycle HC2 will be described in order starting from point B1, which indicates the position in the compressor 62 at which the secondary-side refrigerant REF2 is taken in.

During heating, when the compressor 62 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 rises and the temperature of the secondary-side refrigerant REF2 rises. Therefore, in FIG. 4, when the compressor 62 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2. Specifically, from point B1 to point B2, the temperature of the secondary-side refrigerant REF2 rises, the enthalpy increases, and the pressure increases.

Next, the secondary-side refrigerant REF2 is cooled by heat exchange with inside IDS air in the indoor heat exchanger 31. Therefore, in FIG. 4, when the secondary-side refrigerant REF2 is cooled in the indoor heat exchanger 31, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B4 as indicated in the section HX3. Specifically, from point B2 to point B3, the pressure is constant, and the temperature of the secondary-side refrigerant REF2 decreases and the enthalpy decreases.

Next, the pressure of the secondary-side refrigerant REF2 decreases as it is depressurized at the expansion valve 72. Therefore, in FIG. 4, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 72, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4. Specifically, from point B3 to point B4, the enthalpy of the secondary-side refrigerant REF2 remains constant and the pressure decreases.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with the heated primary-side refrigerant REF1 in the intermediate heat exchanger 51. The secondary-side refrigerant REF2 is heated by exchanging heat with the return air RA in the exhaust heat exchanger 41. Therefore, in FIG. 4, when the secondary-side refrigerant REF2 is heated in the intermediate heat exchanger 51 and the exhaust heat exchanger 41, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1. Specifically, from point B4 to point B1, the pressure is constant, and the temperature of the secondary-side refrigerant REF2 rises and the enthalpy increases. In FIG. 4, the section HX5 indicates a section heated by the intermediate heat exchanger 51, and the section HX4 indicates a section heated by the exhaust heat exchanger 41.

SUMMARY

According to the air conditioning system 1 according to the present embodiment, the efficiency can be improved by combining an air conditioning apparatus equipped with a binary cycle with a ventilation apparatus that recovers heat at an intermediate pressure.

For example, a low-GWP refrigerant may be used in an air conditioning system to reduce the global warming potential (GWP). Because many low-GWP refrigerants are combustible, there is a limit on the total amount of refrigerants introduced into a room. Therefore, there is a problem that the capacity for temperature control is limited. To solve the problem that the capacity is limited, a method of introducing a non-combustible refrigerant into a room by using an air conditioning apparatus having a binary cycle is considered. However, the efficiency of the binary cycle may be lower than that of a single-stage cycle because the binary cycle has an intermediate heat exchanger.

According to the air conditioning system 1 according to the present embodiment, an efficient air conditioning system can be provided by combining an air conditioner equipped with a binary cycle with a ventilation apparatus that recovers heat from exhaust with a refrigerant.

The compressor 61 is an example of a first compressor, the outdoor heat exchanger 11 is an example of a first heat exchanger, the air supply path P1 is an example of a first path, and the air supply heat exchanger 21 is an example of a second heat exchanger. The expansion valve 71 is an example of a first expansion valve, the primary-side refrigerant REF1 is an example of a first refrigerant, the primary-side refrigerant pipe 81 is an example of a first refrigerant pipe, and the primary-side refrigerant circuit CIR1 is an example of a first refrigerant circuit. The compressor 62 is an example of a second compressor, the indoor heat exchanger 31 is an example of a third heat exchanger, the exhaust path P2 is an example of a second path, and the exhaust heat exchanger 41 is an example of a fourth heat exchanger. The expansion valve 72 is an example of a second expansion valve, the secondary-side refrigerant REF2 is an example of a second refrigerant, the secondary-side refrigerant pipe 82 is an example of a second refrigerant pipe, and the secondary-side refrigerant circuit CIR2 is an example of a second refrigerant circuit. The intermediate heat exchanger 51 is an example of a first intermediate heat exchanger.

<<Air Conditioning System 2 According to a Second Embodiment>>

An air conditioning system 2 according to the second embodiment will be described below. FIG. 5 is a diagram illustrating a schematic configuration of the air conditioning system 2 according to the second embodiment. FIG. 6 is a diagram explaining the primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR12 in the air conditioning system 2 according to the second embodiment. The air conditioning system 2 provides ventilation between the inside IDS and the outside OPS of the building BLD. The air conditioning system 2 provides air conditioning in the inside IDS of the building BLD.

<Configuration of the Air Conditioning System 2>

The air conditioning system 2 includes the outdoor unit 10, an air supply unit 120, the indoor unit 30, the exhaust unit 40, and the heat exchange unit 50. The air conditioning system 2 includes the compressor 61, the compressor 62, the expansion valve 71, the expansion valve 72, and an expansion valve 73.

The air conditioning system 2 is provided with the air supply unit 120 in place of the air supply unit 20 of the air conditioning system 1. Here, the same configuration as that of the air conditioning system 1 will be omitted and the air supply unit 120 will be described.

[Air Supply Unit 120]

The air supply unit 120 takes in outside air OA from the outside OPS of the building BLD, and exchanges heat between the captured outside air OA and the primary-side refrigerant REF1. The air supply unit 120 then supplies the outside air OA after heat exchange to the inside IDS of the building BLD as the supply air SA. The air supply unit 120 includes the air supply heat exchanger 21, the fan 22, and a second air supply heat exchanger 23. Because the air supply heat exchanger 21 and the fan 22 have the same configuration as that in the air conditioning system 1, their descriptions are omitted.

The second air supply heat exchanger 23 is provided downstream of the air supply heat exchanger 21 in the air supply path P1. The second air supply heat exchanger 23 exchanges heat between the outside air OA passed through the air supply heat exchanger 21 and the secondary-side refrigerant REF2. The second air supply heat exchanger 23 includes a plurality of plate-type fins and a pipe that penetrate the fins and through which the secondary-side refrigerant REF2 flows.

The secondary-side refrigerant REF2 flows through the pipe of the second air supply heat exchanger 23. When the outside air OA flows between the fins of the second air supply heat exchanger 23, heat exchange is performed between the outside air OA and the secondary-side refrigerant REF2 flowing through the pipe of the second air supply heat exchanger 23.

<Primary-Side Refrigerant Circuit CIR1 and Secondary-Side Refrigerant Circuit CIR12>

The primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR12 in the air conditioning system 2 will be described below. FIG. 6 is a diagram for explaining the primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR12 in the air conditioning system 2 according to the second embodiment. In FIG. 6, the arrows of the primary-side refrigerant REF1 and the secondary-side refrigerant REF2 indicate the direction in which the refrigerant flows during cooling.

The air conditioning system 2 includes the primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR12. The primary-side refrigerant circuit CIR1 and the secondary-side refrigerant circuit CIR12 are thermally connected via an intermediate heat exchanger 51. Because the primary-side refrigerant circuit CIR1 has the same configuration as the air conditioning system 1, a description thereof is omitted.

[Secondary-Side Refrigerant Circuit CIR12]

The secondary-side refrigerant circuit CIR12 includes the compressor 62, the second air supply heat exchanger 23, the indoor heat exchanger 31, the exhaust heat exchanger 41, the intermediate heat exchanger 51, the expansion valve 72, and the expansion valve 73 connected via a secondary-side refrigerant pipe 182. In the secondary-side refrigerant circuit CIR12, the secondary-side refrigerant REF2 flows therein via the secondary-side refrigerant pipe 182. The secondary-side refrigerant circuit CIR12 constitutes the secondary-side refrigeration cycle HC12 described below.

In the secondary-side refrigerant circuit CIR12, the intermediate heat exchanger 51 and the exhaust heat exchanger 41 are connected in this order from the compressor 62. In the secondary-side refrigerant circuit CIR12, following the exhaust heat exchanger 41, the expansion valve 72 and the indoor heat exchanger 31 are connected in parallel with the expansion valve 73 and the second air supply heat exchanger 23. Then, the secondary-side refrigerant circuit CIR12 returns to the compressor 62 from the indoor heat exchanger 31 and the second air supply heat exchanger 23.

During cooling, in the secondary-side refrigerant circuit CIR12, the secondary-side refrigerant REF2 compressed and heated by the compressor 62 flows in order from the compressor 62 to the intermediate heat exchanger 51 and the exhaust heat exchanger 41. Then, the secondary-side refrigerant REF2 discharged from the exhaust heat exchanger 41 branches into the expansion valve 72 and the expansion valve 73. The secondary-side refrigerant REF2 is depressurized at the expansion valve 72 and the expansion valve 73, respectively. The secondary-side refrigerant REF2 depressurized at the expansion valve 72 flows from the expansion valve 72 to the indoor heat exchanger 31. The secondary-side refrigerant REF2 depressurized at the expansion valve 73 flows from the expansion valve 73 to the second air supply heat exchanger 23. The secondary-side refrigerant REF2 that has passed through the indoor heat exchanger 31 and the second air supply heat exchanger 23 returns to the compressor 62.

During heating, in the secondary-side refrigerant circuit CIR12, the secondary-side refrigerant REF2 that has been compressed and heated by the compressor 62 flows divergently from the compressor 62 to the indoor heat exchanger 31 and the second air supply heat exchanger 23. The secondary-side refrigerant REF2 that has passed through the indoor heat exchanger 31 is depressurized at the expansion valve 72. The secondary-side refrigerant REF2 that has passed through the second air supply heat exchanger 23 is depressurized at the expansion valve 73. The secondary-side refrigerant REF2 that has been depressurized in each of the expansion valves 72 and 73 merges. The merged secondary-side refrigerant REF2 flows to the exhaust heat exchanger 41 and the intermediate heat exchanger 51. The secondary-side refrigerant REF2 that has passed through the intermediate heat exchanger 51 returns to the compressor 62.

<Primary-Side Refrigeration Cycle HC1 and Secondary-Side Refrigeration Cycle HC12>

The primary-side refrigeration cycle HC1 in the primary-side refrigerant circuit CIR1 and the secondary-side refrigeration cycle HC12 in the secondary-side refrigerant circuit CIR12 will be described below. FIG. 7 is a diagram for explaining the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC12 during cooling by the air conditioning system 2 according to the second embodiment. FIG. 8 is a diagram for explaining the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC12 during heating by the air conditioning system 2 according to the second embodiment.

FIGS. 7 and 8 are diagrams schematically illustrating the primary-side refrigeration cycle HC1 and the secondary-side refrigeration cycle HC12 in an enthalpy-pressure diagram (Mollier diagram). FIGS. 7 and 8 are diagrams for explaining the operation, and the refrigeration cycle is simplified. The horizontal axis in each of FIGS. 7 and 8 indicate the enthalpy. The vertical axis in each of FIGS. 7 and 8 indicate the pressure. The description of the primary-side refrigeration cycle HC1 is omitted because it is the same refrigeration cycle as the primary-side refrigeration cycle HC1 in the air conditioning system 1.

First, the secondary-side refrigeration cycle HC12 of the air conditioning system 2 according to the second embodiment during cooling will be described with reference to FIG. 7.

With regard to the secondary-side refrigeration cycle HC12, the points B1 to B3, which indicate the position in the compressor 62 at which the secondary-side refrigerant REF2 is taken in, are the same as those of the air conditioning system 1, so the description will be omitted.

At point B3, the pressure of the secondary-side refrigerant REF2 is reduced by being depressurized at the expansion valve 72 and the expansion valve 73, respectively. In FIG. 7, the parallel circuit portion formed by the expansion valve 72 and the indoor heat exchanger 31, and the expansion valve 73 and the second air supply heat exchanger 23, in the secondary-side refrigerant circuit CIR12, is expressed by a single line. Therefore, in FIG. 3, as the secondary-side refrigerant REF2 is depressurized at the expansion valve 72 and the expansion valve 73, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with inside IDS air in the indoor heat exchanger 31 and heated by exchanging heat with outside air OA in the second air supply heat exchanger 23. Therefore, in FIG. 3, as the secondary-side refrigerant REF2 is heated in the indoor heat exchanger 31 and the second air supply heat exchanger 23, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1, as indicated in the section HX3+HX2a. Specifically, at points B4 to B1, the pressure is constant, and the temperature of the secondary-side refrigerant REF2 rises and the enthalpy increases.

Next, the secondary-side refrigeration cycle HC12 of the air conditioning system 2 according to the second embodiment during heating will be described with reference to FIG. 8. In FIG. 8, the parallel circuit portion formed by the expansion valve 72 and the indoor heat exchanger 31, and the expansion valve 73 and the second air supply heat exchanger 23, in the secondary-side refrigerant circuit CIR12, is expressed by a single line.

With regard to the secondary-side refrigeration cycle HC12, from the point B1 to the point B2 and from the point B3 to the point B4, which points indicate the positions in the compressor 62 at which the secondary-side refrigerant REF2 is taken in, are the same as those in the air conditioning system 1, and therefore the description will be omitted.

The secondary-side refrigerant REF2 is cooled by exchanging heat with inside IDS air in the indoor heat exchanger 31. The secondary-side refrigerant REF2 is cooled by exchanging heat with outside air OA in the second air supply heat exchanger 23. Therefore, in FIG. 8, when the secondary-side refrigerant REF2 is cooled in the indoor heat exchanger 31 and the second air supply heat exchanger 23, the enthalpy and pressure of the secondary-side refrigerant REF2 change from the point B2 to the point B3 as illustrated in the section HX3+HX2a. Specifically, from point B2 to point B3, the pressure is constant, and the temperature of the secondary-side refrigerant REF2 decreases and the enthalpy decreases.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valves 72 and 73, respectively. Therefore, in FIG. 8, when the secondary-side refrigerant REF2 is depressurized at the expansion valves 72 and 73, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

SUMMARY

According to the air conditioning system 2 according to the present embodiment, in addition to the effects and functions of the air conditioning system 1, the efficiency can be improved by adjusting the temperature of the air supply unit by using the secondary-side refrigerant REF2.

The second air supply heat exchanger 23 is an example of a sixth heat exchanger.

<<Ventilation Apparatus 3 According to a Third Embodiment>>

A ventilation apparatus 3 according to the third embodiment will be described below. The ventilation apparatus 3 includes a primary-side refrigeration cycle HC21 including the outdoor heat exchanger 11 and a secondary-side refrigeration cycle HC22 including the air supply heat exchanger 21. FIG. 9 is a diagram illustrating a schematic configuration of the ventilation apparatus 3 according to the third embodiment. FIG. 10 is a diagram explaining the primary-side refrigerant circuit CIR21 and the secondary-side refrigerant circuit CIR22 in the ventilation apparatus 3 according to the third embodiment. The ventilation apparatus 3 performs ventilation between the inside IDS and the outside OPS of the building BLD.

<Configuration of the Ventilation Apparatus 3>

The ventilation apparatus 3 includes the outdoor unit 10, the air supply unit 20, the exhaust unit 40, and the heat exchange unit 50. The ventilation apparatus 3 also includes a compressor 261, a compressor 262, an expansion valve 271, and an expansion valve 272.

Because the ventilation apparatus 3 has the same configuration as the air conditioning system 1, details thereof can be found in the above descriptions, and the refrigerant circuit of the ventilation apparatus 3 will be described.

<Primary-Side Refrigerant Circuit CIR21 and Secondary-Side Refrigerant Circuit CIR22>

The primary-side refrigerant circuit CIR21 and the secondary-side refrigerant circuit CIR22 in the ventilation apparatus 3 will be described. FIG. 10 is a diagram for explaining the primary-side refrigerant circuit CIR21 and secondary-side refrigerant circuit CIR22 in the ventilation apparatus 3 according to the third embodiment. In FIG. 10, the arrows of the primary-side refrigerant REF1 and the secondary-side refrigerant REF2 indicate the direction in which the refrigerant flows during cooling.

The ventilation apparatus 3 includes the primary-side refrigerant circuit CIR21 and the secondary-side refrigerant circuit CIR22. The primary-side refrigerant circuit CIR21 and the secondary-side refrigerant circuit CIR22 are thermally connected via an intermediate heat exchanger 51.

[Primary-Side Refrigerant Circuit CIR21]

The primary-side refrigerant circuit CIR21 includes the compressor 261, the outdoor heat exchanger 11, the intermediate heat exchanger 51, and the expansion valve 271 connected by a primary-side refrigerant pipe 281. In the primary-side refrigerant circuit CIR21, the primary-side refrigerant REF1 flows therein via the primary-side refrigerant pipe 281. The primary-side refrigerant circuit CIR21 constitutes a primary-side refrigeration cycle HC21 described below.

The primary-side refrigerant circuit CIR21 is connected to the outdoor heat exchanger 211, the expansion valve 271, and the intermediate heat exchanger 51 in this order from the compressor 261, returning to the compressor 261.

During cooling, in the primary-side refrigerant circuit CIR21, the primary-side refrigerant REF1 compressed and heated by the compressor 261 flows in order from the compressor 261 to the outdoor heat exchanger 11 and the expansion valve 271. The primary-side refrigerant REF1 is depressurized at the expansion valve 271. The depressurized primary-side refrigerant REF1 flows from the expansion valve 271 to the intermediate heat exchanger 51. The primary-side refrigerant REF1 that has passed through the intermediate heat exchanger 51 returns to the compressor 261.

During heating, the primary-side refrigerant REF1 that has been compressed and heated by the compressor 261 in the primary-side refrigerant circuit CIR21 flows from the compressor 261 to the intermediate heat exchanger 51 and the expansion valve 271 in this order. The primary-side refrigerant REF1 is depressurized at the expansion valve 271. The depressurized primary-side refrigerant REF1 flows from the expansion valve 271 to the outdoor heat exchanger 11. The primary-side refrigerant REF1 that has passed through the outdoor heat exchanger 11 returns to the compressor 261.

[Secondary-Side Refrigerant Circuit CIR22]

The secondary-side refrigerant circuit CIR22 includes the compressor 262, the air supply heat exchanger 21, the exhaust heat exchanger 41, the intermediate heat exchanger 51, and the expansion valve 272 connected by a secondary-side refrigerant pipe 282. In the secondary-side refrigerant circuit CIR22, the secondary-side refrigerant REF2 flows therein via the secondary-side refrigerant pipe 282. The secondary-side refrigerant circuit CIR22 constitutes the secondary-side refrigeration cycle HC22 described below.

In the secondary-side refrigerant circuit CIR22, the exhaust heat exchanger 41, the intermediate heat exchanger 51, the expansion valve 272, and the air supply heat exchanger 21 are connected in this order from the compressor 262, returning to the compressor 262.

During cooling, in the secondary-side refrigerant circuit CIR22, the secondary-side refrigerant REF2 compressed and heated by the compressor 262 flows in order from the compressor 262 to the exhaust heat exchanger 41, the intermediate heat exchanger 51, and the expansion valve 272. The secondary-side refrigerant REF2 is depressurized at the expansion valve 272. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 272 to the air supply heat exchanger 21. The secondary-side refrigerant REF2 that has passed through the air supply heat exchanger 21 returns to the compressor 262.

During heating, in the secondary-side refrigerant circuit CIR22, the secondary-side refrigerant REF2 compressed and heated by the compressor 262 flows from the compressor 262 to the air supply heat exchanger 21 and the expansion valve 272 in this order. The secondary-side refrigerant REF2 is depressurized at the expansion valve 272. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 272 to the intermediate heat exchanger 51 and the exhaust heat exchanger 41 in this order. The secondary-side refrigerant REF2 that has passed through the exhaust heat exchanger 41 returns to the compressor 262.

<Primary-Side Refrigeration Cycle HC21 and Secondary-Side Refrigeration Cycle HC22>

The primary-side refrigeration cycle HC21 in the primary-side refrigerant circuit CIR21 and the secondary-side refrigeration cycle HC22 in the secondary-side refrigerant circuit CIR22 will be described. FIG. 11 is a diagram for explaining the primary-side refrigeration cycle HC21 and the secondary-side refrigeration cycle HC22 during cooling by the ventilation apparatus 3 according to the third embodiment. FIG. 12 is a diagram for explaining the primary-side refrigeration cycle HC21 and the secondary-side refrigeration cycle HC22 during heating by the ventilation apparatus 3 according to the third embodiment.

FIGS. 11 and 12 are diagrams schematically illustrating the primary-side refrigeration cycle HC21 and the secondary-side refrigeration cycle HC22 in an enthalpy-pressure diagram (Mollier diagram). FIGS. 11 and 12 are diagrams for explaining the operation, and the refrigeration cycle is illustrated in a simplified form. The horizontal axis in each of FIGS. 11 and 12 indicates enthalpy. The vertical axis in each of FIGS. 11 and 12 indicates pressure.

First, the primary-side refrigeration cycle HC21 and the secondary-side refrigeration cycle HC22 of the ventilation apparatus 3 according to the third embodiment during cooling will be described with reference to FIG. 11.

First, the primary-side refrigeration cycle HC21 will be described in order from point A1, which indicates the position in the compressor 261 at which the primary-side refrigerant REF1 is taken in.

When the compressor 261 compresses the primary-side refrigerant REF1 during cooling, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 11, when the compressor 261 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 11, when the primary-side refrigerant REF1 is cooled in the outdoor heat exchanger 11, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3, as indicated in the section HX1.

Next, the pressure of the primary-side refrigerant REF1 decreases by being depressurized at the expansion valve 271. Therefore, in FIG. 11, when the primary-side refrigerant REF1 is depressurized at the expansion valve 271, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with the heated secondary-side refrigerant REF2 in the intermediate heat exchanger 51. Therefore, in FIG. 11, when the primary-side refrigerant REF1 is heated in the intermediate heat exchanger 51, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1. The section HX5 in FIG. 11 indicates the section heated by the intermediate heat exchanger 51.

Next, the secondary-side refrigeration cycle HC22 will be described in order from point B1, which indicates the position in the compressor 262 at which the secondary-side refrigerant REF2 is taken in.

During cooling, when the compressor 262 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature also increases. Therefore, in FIG. 11, when the compressor 262 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the return air RA in the exhaust heat exchanger 41. The secondary-side refrigerant REF2 is cooled by exchanging heat with the cooled primary-side refrigerant REF1 in the intermediate heat exchanger 51. Therefore, in FIG. 11, when the secondary-side refrigerant REF2 is cooled in the exhaust heat exchanger 41 and the intermediate heat exchanger 51, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B3. In FIG. 11, the section HX4 indicates the section cooled by the exhaust heat exchanger 41, and the section HX5 indicates the section cooled by the intermediate heat exchanger 51.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valve 272. Therefore, in FIG. 11, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 272, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with the outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 11, when the secondary-side refrigerant REF2 is heated in the air supply heat exchanger 21, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1 as indicated in the section HX2.

Next, with reference to FIG. 12, the primary-side refrigeration cycle HC21 and the secondary-side refrigeration cycle HC22 of the ventilation apparatus 3 according to the third embodiment during heating will be described.

First, the primary-side refrigeration cycle HC21 will be described in order from point A1, which indicates the position in the compressor 261 at which the primary-side refrigerant REF1 is taken in.

During heating, when the compressor 261 compresses the primary-side refrigerant REF1, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 12, when the compressor 261 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with the cooled secondary-side refrigerant REF2 in the intermediate heat exchanger 51. Therefore, in FIG. 12, when the primary-side refrigerant REF1 is cooled in the intermediate heat exchanger 51, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3. The section HX5 in FIG. 12 indicates the section cooled by the intermediate heat exchanger 51.

Next, the pressure of the primary-side refrigerant REF1 decreases by being depressurized at the expansion valve 271. Therefore, in FIG. 12, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4 when the primary-side refrigerant REF1 is depressurized at the expansion valve 271.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 12, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1 as indicated in the section HX1 when the primary-side refrigerant REF1 is heated in the outdoor heat exchanger 11.

Next, the secondary-side refrigeration cycle HC22 will be described in order from point B1, which indicates the position in the compressor 262 where the secondary-side refrigerant REF2 is taken in.

During heating, when the compressor 262 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature of the secondary-side refrigerant REF2 also increases. Therefore, in FIG. 12, when the compressor 262 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 12, when the secondary-side refrigerant REF2 is cooled in the air supply heat exchanger 21, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B3 as indicated in the section HX2.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valve 272. Therefore, in FIG. 12, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 272, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with the heated primary-side refrigerant REF1 in the intermediate heat exchanger 51. The secondary-side refrigerant REF2 is heated by exchanging heat with the return air RA in the exhaust heat exchanger 41. Therefore, in FIG. 12, when the secondary-side refrigerant REF2 is heated in the intermediate heat exchanger 51 and the exhaust heat exchanger 41, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1. In FIG. 12, the section HX5 indicates the section heated by the intermediate heat exchanger 51, and the section HX4 indicates the section heated by the exhaust heat exchanger 41.

SUMMARY

According to the ventilation apparatus 3 according to the third embodiment, by using an outdoor unit, the outside air OA can be efficiently taken in and the temperature can be adjusted.

For example, under low temperature outside air conditions in a cold region, the temperature of the outside air OA is low, and there is a possibility that the discharge air temperature cannot be ensured up to room temperature. Therefore, according to the ventilation apparatus 3 according to the third embodiment, by using the outdoor heat exchanger 11, sufficient heat radiation can be achieved and energy saving can be improved by lowering the condensation temperature. Further, according to the ventilation apparatus 3 according to the third embodiment, freezing can be reduced during heating.

Further, according to the ventilation apparatus 3 according to the third embodiment, because the air supply unit 20 and the exhaust unit 40 can be separately installed from the outdoor unit 10, the degree of freedom of installation of the apparatus can be increased.

Further, according to the ventilation apparatus 3 according to the third embodiment, the discharge air temperature of the air supply can be maintained appropriately while satisfying the operational area of the heat recovery machine, and energy saving and comfort can both be achieved even in cold regions.

Further, according to the ventilation apparatus 3 according to the third embodiment, a separated external controller can be a heat adjustment heat exchanger for obtaining a heat balance. That is, according to the heat amount in the outdoor heat exchanger 11, the ventilation apparatus 3 according to the third embodiment adjusts the heat balance between the air supply heat exchanger 21 and the exhaust heat exchanger 41.

The primary-side refrigeration cycle HC21 is an example of a first refrigeration cycle, and the secondary-side refrigeration cycle HC22 is an example of a second refrigeration cycle. The compressor 261 is an example of a third compressor, the primary-side refrigerant REF1 is an example of a third refrigerant, the primary-side refrigerant pipe 281 is an example of a third refrigerant pipe, and the primary-side refrigerant circuit CIR21 is an example of a third refrigerant circuit. The compressor 262 is an example of a fourth compressor, the secondary-side refrigerant REF2 is an example of a fourth refrigerant, the secondary-side refrigerant pipe 282 is an example of a fourth refrigerant pipe, and the secondary-side refrigerant circuit CIR22 is an example of a fourth refrigerant circuit. The intermediate heat exchanger 51 is an example of a second intermediate heat exchanger.

<<Ventilation Apparatus 4 According to a Fourth Embodiment>>

The ventilation apparatus 4 according to the fourth embodiment will be described below. FIG. 13 is a diagram illustrating a schematic configuration of the ventilation apparatus 4 according to the fourth embodiment. FIG. 14 is a diagram explaining the primary-side refrigerant circuit CIR31 and the secondary-side refrigerant circuit CIR32 in the ventilation apparatus 4 according to the fourth embodiment. The ventilation apparatus 3 performs ventilation between the inside IDS and the outside OPS of the building BLD.

<Configuration of the Ventilation Apparatus 4>

The ventilation apparatus 4 includes the outdoor unit 10, the air supply unit 20, the exhaust unit 40, and the heat exchange unit 50. The ventilation apparatus 4 also includes a compressor 361, a compressor 362, an expansion valve 371, and an expansion valve 372.

Because the ventilation apparatus 4 has the same configuration as the air conditioning system 1, details thereof can be found in the above descriptions, and the refrigerant circuit of the ventilation apparatus 4 will be described.

<Primary-Side Refrigerant Circuit CIR31 and Secondary-Side Refrigerant Circuit CIR32>

The primary-side refrigerant circuit CIR31 and the secondary-side refrigerant circuit CIR32 in the ventilation apparatus 4 will be described. FIG. 14 is a diagram for explaining the primary-side refrigerant circuit CIR31 and secondary-side refrigerant circuit CIR32 in the ventilation apparatus 4 according to the fourth embodiment. In FIG. 14, the arrows of the primary-side refrigerant REF1 and the secondary-side refrigerant REF2 indicate the direction in which the refrigerant flows during cooling.

The ventilation apparatus 4 includes the primary-side refrigerant circuit CIR31 and the secondary-side refrigerant circuit CIR32. The primary-side refrigerant circuit CIR31 and the secondary-side refrigerant circuit CIR32 are thermally connected via an intermediate heat exchanger 51.

[Primary-Side Refrigerant Circuit CIR31]

The primary-side refrigerant circuit CIR31 includes the compressor 361, the exhaust heat exchanger 41, the outdoor heat exchanger 11, the intermediate heat exchanger 51, and the expansion valve 371 connected by a primary-side refrigerant pipe 381. In the primary-side refrigerant circuit CIR31, the primary-side refrigerant REF1 flows therein via the primary-side refrigerant pipe 381. The primary-side refrigerant circuit CIR31 constitutes a primary-side refrigeration cycle HC31 described below.

The primary-side refrigerant circuit CIR31 is connected to the exhaust heat exchanger 41, the outdoor heat exchanger 11, the expansion valve 371, and the intermediate heat exchanger 51 in this order from the compressor 361, returning to the compressor 361.

During cooling, in the primary-side refrigerant circuit CIR31, the primary-side refrigerant REF1 compressed and heated by the compressor 361 flows from the compressor 361 to the exhaust heat exchanger 41, the outdoor heat exchanger 11, and the expansion valve 371 in this order. The primary-side refrigerant REF1 is depressurized at the expansion valve 371. The depressurized primary-side refrigerant REF1 flows from the expansion valve 371 to the intermediate heat exchanger 51. The primary-side refrigerant REF1 that has passed through the intermediate heat exchanger 51 returns to the compressor 361.

During heating, in the primary-side refrigerant circuit CIR31, the primary-side refrigerant REF1 that has been compressed and heated by the compressor 361 flows from the compressor 361 to the intermediate heat exchanger 51 and the expansion valve 371 in this order. The primary-side refrigerant REF1 is depressurized at the expansion valve 371. The depressurized primary-side refrigerant REF1 flows from the expansion valve 371 to the outdoor heat exchanger 11 and the exhaust heat exchanger 41 in this order. The primary-side refrigerant REF1 that has passed through the outdoor heat exchanger 11 and the exhaust heat exchanger 41 returns to the compressor 361.

[Secondary-Side Refrigerant Circuit CIR32]

The secondary-side refrigerant circuit CIR32 includes the compressor 362, the air supply heat exchanger 21, the intermediate heat exchanger 51, and the expansion valve 372 connected by a secondary-side refrigerant pipe 382. In the secondary-side refrigerant circuit CIR32, the secondary-side refrigerant REF2 flows therein via the secondary-side refrigerant pipe 382. The secondary-side refrigerant circuit CIR32 constitutes a secondary-side refrigeration cycle HC32 described below.

In the secondary-side refrigerant circuit CIR32, the intermediate heat exchanger 51, the expansion valve 372, and the air supply heat exchanger 21 are connected in this order from the compressor 362, returning to the compressor 362.

During cooling, in the secondary-side refrigerant circuit CIR32, the secondary-side refrigerant REF2 compressed and heated by the compressor 362 flows from the compressor 362 to the intermediate heat exchanger 51 and the expansion valve 372 in this order. The secondary-side refrigerant REF2 is depressurized at the expansion valve 372. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 372 to the air supply heat exchanger 21. The secondary-side refrigerant REF2 that has passed through the air supply heat exchanger 21 returns to the compressor 362.

During heating, in the secondary-side refrigerant circuit CIR32, the secondary-side refrigerant REF2 compressed and heated by the compressor 362 flows from the compressor 362 to the air supply heat exchanger 21 and the expansion valve 372 in this order. The secondary-side refrigerant REF2 is depressurized at the expansion valve 372. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 372 to the intermediate heat exchanger 51. The secondary-side refrigerant REF2 that has passed through the intermediate heat exchanger 51 returns to the compressor 362.

<Primary-Side Refrigeration Cycle HC31 and Secondary-Side Refrigeration Cycle HC32>

The primary-side refrigeration cycle HC31 in the primary-side refrigerant circuit CIR31 and the secondary-side refrigeration cycle HC32 in the secondary-side refrigerant circuit CIR32 will be described below. FIG. 15 is a diagram for explaining the primary-side refrigeration cycle HC31 and the secondary-side refrigeration cycle HC32 during cooling by the ventilation apparatus 4 according to the fourth embodiment. FIG. 16 is a diagram for explaining the primary-side refrigeration cycle HC31 and the secondary-side refrigeration cycle HC32 during heating by the ventilation apparatus 4 according to the fourth embodiment.

FIGS. 15 and 16 are diagrams schematically illustrating the primary-side refrigeration cycle HC31 and the secondary-side refrigeration cycle HC32 in an enthalpy-pressure diagram (Mollier diagram). FIGS. 15 and 16 are diagrams for explaining the operation, and the refrigeration cycle is described in a simplified form. The horizontal axis in each of FIGS. 15 and 16 represents enthalpy. The vertical axis in each of FIGS. 15 and 16 represents pressure.

First, the primary-side refrigeration cycle HC31 and the secondary-side refrigeration cycle HC32 of the ventilation apparatus 4 according to the fourth embodiment during cooling will be described with reference to FIG. 15.

First, the primary-side refrigeration cycle HC31 will be described in order from point A1, which indicates the position in the compressor 361 at which the primary-side refrigerant REF1 is taken in.

When the compressor 361 compresses the primary-side refrigerant REF1 during cooling, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 15, when the compressor 361 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with the return air RA in the exhaust heat exchanger 41. The primary-side refrigerant REF1 is cooled by exchanging heat with the outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 15, as the primary-side refrigerant REF1 is cooled in the exhaust heat exchanger 41 and the outdoor heat exchanger 11, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3 as indicated in sections HX4 and HX1.

Next, the pressure of the primary-side refrigerant REF1 decreases by being depressurized at the expansion valve 371. Therefore, in FIG. 15, as the primary-side refrigerant REF1 is depressurized at the expansion valve 371, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with the heated secondary-side refrigerant REF2 in the intermediate heat exchanger 51. Therefore, in FIG. 15, as the primary-side refrigerant REF1 is heated in the intermediate heat exchanger 51, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1. The section HX5 in FIG. 15 indicates the section heated by the intermediate heat exchanger 51.

Next, the secondary-side refrigeration cycle HC32 will be described in order from point B1, which indicates the position in the compressor 362 at which the secondary-side refrigerant REF2 is taken in.

During cooling, when the compressor 362 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature also increases. Therefore, in FIG. 15, when the compressor 262 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the cooled primary-side refrigerant REF1 in the intermediate heat exchanger 51. Therefore, in FIG. 15, when the secondary-side refrigerant REF2 is cooled in the intermediate heat exchanger 51, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B3. Note that the section HX5 in FIG. 15 indicates the section cooled by the intermediate heat exchanger 51.

Next, the pressure of the secondary-side refrigerant REF2 is reduced by being depressurized at the expansion valve 372. Therefore, in FIG. 15, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 372, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 15, when the secondary-side refrigerant REF2 is heated in the air supply heat exchanger 21, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1 as indicated in the section HX2.

Next, with reference to FIG. 16, the primary-side refrigeration cycle HC31 and the secondary-side refrigeration cycle HC32 of the ventilation apparatus 4 according to the fourth embodiment during heating will be described.

First, the primary-side refrigeration cycle HC31 will be described in order from point A1, which indicates the position in the compressor 361 at which the primary-side refrigerant REF1 is taken in.

During heating, when the compressor 361 compresses the primary-side refrigerant REF1, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 16, when the compressor 361 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with the cooled secondary-side refrigerant REF2 in the intermediate heat exchanger 51. Therefore, in FIG. 16, when the primary-side refrigerant REF1 is cooled in the intermediate heat exchanger 51, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3. The section HX5 in FIG. 16 indicates the section cooled by the intermediate heat exchanger 51.

Next, the pressure of the primary-side refrigerant REF1 decreases by being depressurized at the expansion valve 371. Therefore, in FIG. 16, when the primary-side refrigerant REF1 is depressurized at the expansion valve 371, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with the outside air OA in the outdoor heat exchanger 11. The primary-side refrigerant REF1 is heated by exchanging heat with the return air RA in the exhaust heat exchanger 41. Therefore, in FIG. 16, when the primary-side refrigerant REF1 is heated in the outdoor heat exchanger 11 and the exhaust heat exchanger 41, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1 as indicated in sections HX1 and HX4.

Next, the secondary-side refrigeration cycle HC32 will be described in order from point B1, which indicates the position in the compressor 362 where the secondary-side refrigerant REF2 is taken in.

During heating, when the compressor 362 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature of the secondary-side refrigerant REF2 also increases. Therefore, in FIG. 16, when the compressor 362 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 16, when the secondary-side refrigerant REF2 is cooled in the air supply heat exchanger 21, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B3 as indicated in the section HX2.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valve 372. Therefore, in FIG. 16, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 372, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with the heated primary-side refrigerant REF1 in the intermediate heat exchanger 51. Therefore, in FIG. 16, when the secondary-side refrigerant REF2 is heated in the intermediate heat exchanger 51, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1. Note that the section HX5 in FIG. 16 indicates the section heated by the intermediate heat exchanger 51.

SUMMARY

According to the ventilation apparatus 4 according to the fourth embodiment, the outside air OA can be efficiently taken in and the temperature can be adjusted by using an outdoor unit, in the same manner as in the ventilation apparatus 3.

The primary-side refrigeration cycle HC31 is an example of a first refrigeration cycle, and the secondary-side refrigeration cycle HC32 is an example of a second refrigeration cycle. The compressor 361 is an example of a fifth compressor, the primary-side refrigerant REF1 is an example of a fifth refrigerant, the primary-side refrigerant pipe 381 is an example of a fifth refrigerant pipe, and the primary-side refrigerant circuit CIR31 is an example of a fifth refrigerant circuit. The compressor 362 is an example of a sixth compressor, the secondary-side refrigerant REF2 is an example of a sixth refrigerant, the secondary-side refrigerant pipe 382 is an example of a sixth refrigerant pipe, and the secondary-side refrigerant circuit CIR32 is an example of a sixth refrigerant circuit. The intermediate heat exchanger 51 is an example of a third intermediate heat exchanger.

<<Air Conditioning System 5 According to a Fifth Embodiment>>

An air conditioning system 5 according to the fifth embodiment will be described below. FIG. 17 is a diagram illustrating a schematic configuration of the air conditioning system 5 according to the fifth embodiment. FIG. 18 is a diagram explaining a primary-side refrigerant circuit CIR41 and a secondary-side refrigerant circuit CIR42 in the air conditioning system 5 according to the fifth embodiment. The ventilation apparatus 3 provides ventilation between the inside IDS and the outside OPS of the building BLD.

<Configuration of the Air Conditioning System 5>

The air conditioning system 5 includes the outdoor unit 10, the air supply unit 20, the indoor unit 30, the exhaust unit 40, and the heat exchange unit 50. The air conditioning system 5 also includes a compressor 461 and a compressor 462, a four-way valve 463 and a four-way valve 464, and an expansion valve 471 and an expansion valve 472. The outdoor unit 10, the compressor 461, and the four-way valve 463 may be collectively referred to as an outdoor unit 100. The compressor 462 and the four-way valve 464 may be collectively referred to as a compressor 466.

Because the air conditioning system 5 has the same configuration as the air conditioning system 1, details thereof can be found in the above descriptions, and the refrigerant circuit of the air conditioning system 5 will be described.

<Primary-Side Refrigerant Circuit CIR41 and Secondary-Side Refrigerant Circuit CIR42>

The primary-side refrigerant circuit CIR41 and the secondary-side refrigerant circuit CIR42 in the air conditioning system 5 will be described. FIG. 18 is a diagram for explaining the primary-side refrigerant circuit CIR41 and the secondary-side refrigerant circuit CIR42 in the air conditioning system 5 according to the fifth embodiment. In FIG. 18, the arrows of the primary-side refrigerant REF1 and the secondary-side refrigerant REF2 indicate the direction in which the refrigerant flows during cooling.

The air conditioning system 5 includes the primary-side refrigerant circuit CIR41 and the secondary-side refrigerant circuit CIR42. The primary-side refrigerant circuit CIR41 and the secondary-side refrigerant circuit CIR42 are thermally connected via an intermediate heat exchanger 51.

[Primary-Side Refrigerant Circuit CIR41]

The primary-side refrigerant circuit CIR41 includes the compressor 461, the outdoor heat exchanger 11, the indoor heat exchanger 31, the intermediate heat exchanger 51, and the expansion valve 471 connected by a primary-side refrigerant pipe 481. In the primary-side refrigerant circuit CIR41, the primary-side refrigerant REF1 flows therein via the primary-side refrigerant pipe 481. The primary-side refrigerant circuit CIR41 constitutes a primary-side refrigeration cycle HC41 described below.

The primary-side refrigerant circuit CIR41 is connected to the outdoor heat exchanger 11, the expansion valve 471, the indoor heat exchanger 31, and the intermediate heat exchanger 51 in order from the compressor 461, returning to the compressor 461.

During cooling, in the primary-side refrigerant circuit CIR41, the primary-side refrigerant REF1 compressed and heated by the compressor 461 flows in order from the compressor 461 to the outdoor heat exchanger 11 and the expansion valve 471. The primary-side refrigerant REF1 is depressurized at the expansion valve 471. The depressurized primary-side refrigerant REF1 flows in order from the expansion valve 471 to the indoor heat exchanger 31 and the intermediate heat exchanger 51. The primary-side refrigerant REF1 that has passed through the indoor heat exchanger 31 and the intermediate heat exchanger 51 returns to the compressor 461.

During heating, in the primary-side refrigerant circuit CIR41, the primary-side refrigerant REF1 that has been compressed and heated by the compressor 461 flows from the compressor 461 to the intermediate heat exchanger 51, the indoor heat exchanger 31, and the expansion valve 471 in this order. The primary-side refrigerant REF1 is depressurized at the expansion valve 471. The depressurized primary-side refrigerant REF1 flows from the expansion valve 471 to the outdoor heat exchanger 11. The primary-side refrigerant REF1 that has passed through the outdoor heat exchanger 11 returns to the compressor 461.

[Secondary-Side Refrigerant Circuit CIR42]

The secondary-side refrigerant circuit CIR42 includes the compressor 462, the air supply heat exchanger 21, the exhaust heat exchanger 41, the intermediate heat exchanger 51, and the expansion valve 472 connected by a secondary-side refrigerant pipe 482. In the secondary-side refrigerant circuit CIR42, a secondary-side refrigerant REF2 flows therein via the secondary-side refrigerant pipe 482. The secondary-side refrigerant circuit CIR42 constitutes a secondary-side refrigeration cycle HC42 described below.

In the secondary-side refrigerant circuit CIR42, the intermediate heat exchanger 51, the exhaust heat exchanger 41, the expansion valve 472, and the air supply heat exchanger 21 are connected in this order from the compressor 462, returning to the compressor 462.

During cooling, in the secondary-side refrigerant circuit CIR42, the secondary-side refrigerant REF2 compressed and heated by the compressor 462 flows in order from the compressor 462 to the intermediate heat exchanger 51, the exhaust heat exchanger 41, and the expansion valve 472. The secondary-side refrigerant REF2 is depressurized at the expansion valve 472. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 472 to the air supply heat exchanger 21. The secondary-side refrigerant REF2 that has passed through the air supply heat exchanger 21 returns to the compressor 462.

During heating, in the secondary-side refrigerant circuit CIR42, the secondary-side refrigerant REF2 compressed and heated by the compressor 462 flows from the compressor 462 to the air supply heat exchanger 21 and the expansion valve 472 in this order. The secondary-side refrigerant REF2 is depressurized at the expansion valve 472. The depressurized secondary-side refrigerant REF2 flows from the expansion valve 472 to the exhaust heat exchanger 41 and the intermediate heat exchanger 51 in this order. The secondary-side refrigerant REF2 which has passed through the exhaust heat exchanger 41 and the intermediate heat exchanger 51 returns to the compressor 462.

<Primary-Side Refrigeration Cycle HC41 and Secondary-Side Refrigeration Cycle HC42>

The primary-side refrigeration cycle HC41 in the primary-side refrigerant circuit CIR41 and the secondary-side refrigeration cycle HC42 in the secondary-side refrigerant circuit CIR42 will be described below. FIG. 19 is a diagram for explaining the primary-side refrigeration cycle HC41 and the secondary-side refrigeration cycle HC42 during cooling by the air conditioning system 5 according to the fifth embodiment. FIG. 20 is a diagram for explaining the primary-side refrigeration cycle HC41 and the secondary-side refrigeration cycle HC42 during heating by the air conditioning system 5 according to the fifth embodiment.

FIGS. 19 and 20 are diagrams schematically illustrating the primary-side refrigeration cycle HC41 and the secondary-side refrigeration cycle HC42 in an enthalpy-pressure diagram (Mollier diagram). FIGS. 19 and 20 are diagrams for explaining the operation, and the refrigeration cycle is described in a simplified form. The horizontal axis in each of FIGS. 19 and 20 indicates enthalpy. The vertical axis in each of FIGS. 19 and 20 indicates pressure.

First, the primary-side refrigeration cycle HC41 and the secondary-side refrigeration cycle HC42 of the air conditioning system 5 according to the fifth embodiment during cooling will be described with reference to FIG. 19.

First, the primary-side refrigeration cycle HC41 will be described in order from point A1, which indicates the position in the compressor 461 at which the primary-side refrigerant REF1 is taken in.

When the compressor 461 compresses the primary-side refrigerant REF1 during cooling, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 19, when the compressor 461 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 19, when the primary-side refrigerant REF1 is cooled in the outdoor heat exchanger 11, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3 as indicated in the section HX1.

Next, the pressure of the primary-side refrigerant REF1 decreases by being depressurized at the expansion valve 471. Therefore, in FIG. 19, when the primary-side refrigerant REF1 is depressurized at the expansion valve 471, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with inside IDS air in the indoor heat exchanger 31. The primary-side refrigerant REF1 is heated by exchanging heat with heated secondary-side refrigerant REF2 in the intermediate heat exchanger 51. Therefore, in FIG. 19, when the primary-side refrigerant REF1 is heated in the indoor heat exchanger 31 and the intermediate heat exchanger 51, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1. In FIG. 19, the section HX3 indicates the section heated by the inside IDS air, and the section HX5 indicates the section heated by the intermediate heat exchanger 51.

Next, the secondary-side refrigeration cycle HC42 will be described in order from point B1, which indicates the position in the compressor 462 at which the secondary-side refrigerant REF2 is taken in.

During cooling, when the compressor 462 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature increases. Therefore, in FIG. 19, when the compressor 462 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the return air RA in the exhaust heat exchanger 41. The secondary-side refrigerant REF2 is cooled by exchanging heat with the cooled primary-side refrigerant REF1 in the intermediate heat exchanger 51. Therefore, in FIG. 19, when the secondary-side refrigerant REF2 is cooled in the exhaust heat exchanger 41 and the intermediate heat exchanger 51, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B3. In FIG. 19, the section HX4 indicates the section cooled by the exhaust heat exchanger 41, and the section HX5 indicates the section cooled by the intermediate heat exchanger 51.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valve 472. Therefore, in FIG. 19, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 472, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with the outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 19, when the secondary-side refrigerant REF2 is heated in the air supply heat exchanger 21, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1 as indicated in the section HX2.

Next, referring to FIG. 20, the primary-side refrigeration cycle HC41 and the secondary-side refrigeration cycle HC42 of the air conditioning system 5 according to the fifth embodiment during heating will be described.

First, the primary-side refrigeration cycle HC41 will be described in order from point A1, which indicates the position in the compressor 461 at which the primary-side refrigerant REF1 is taken in.

During heating, when the compressor 461 compresses the primary-side refrigerant REF1, the pressure of the primary-side refrigerant REF1 increases and the temperature of the primary-side refrigerant REF1 also increases. Therefore, in FIG. 20, when the compressor 461 compresses the primary-side refrigerant REF1, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A1 to point A2.

Next, the primary-side refrigerant REF1 is cooled by exchanging heat with the inside IDS air in the indoor heat exchanger 31. The primary-side refrigerant REF1 is cooled by exchanging heat with the cooled secondary-side refrigerant REF2 in the intermediate heat exchanger 51. Therefore, in FIG. 20, when the primary-side refrigerant REF1 is cooled in the indoor heat exchanger 31 and the intermediate heat exchanger 51, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A2 to point A3. In FIG. 20, the section HX3 indicates the section cooled by the indoor heat exchanger 31, and the section HX5 indicates the section cooled by the intermediate heat exchanger 51.

Next, the pressure of the primary-side refrigerant REF1 is reduced by being depressurized at the expansion valve 471. Therefore, in FIG. 20, when the primary-side refrigerant REF1 is depressurized at the expansion valve 471, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A3 to point A4.

Next, the primary-side refrigerant REF1 is heated by exchanging heat with outside air OA in the outdoor heat exchanger 11. Therefore, in FIG. 20, when the primary-side refrigerant REF1 is heated in the outdoor heat exchanger 11, the enthalpy and pressure of the primary-side refrigerant REF1 change from point A4 to point A1 as indicated in the section HX1.

Next, the secondary-side refrigeration cycle HC42 will be described in order from point B1, which indicates the position in the compressor 462 where the secondary-side refrigerant REF2 is taken in.

During heating, when the compressor 462 compresses the secondary-side refrigerant REF2, the pressure of the secondary-side refrigerant REF2 increases and the temperature of the secondary-side refrigerant REF2 also increases. Therefore, in FIG. 20, when the compressor 462 compresses the secondary-side refrigerant REF2, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B1 to point B2.

Next, the secondary-side refrigerant REF2 is cooled by exchanging heat with the outside air OA in the air supply heat exchanger 21. Therefore, in FIG. 20, when the secondary-side refrigerant REF2 is cooled in the air supply heat exchanger 21, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B2 to point B3 as indicated in the section HX2.

Next, the pressure of the secondary-side refrigerant REF2 decreases by being depressurized at the expansion valve 472. Therefore, in FIG. 20, when the secondary-side refrigerant REF2 is depressurized at the expansion valve 472, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B3 to point B4.

Next, the secondary-side refrigerant REF2 is heated by exchanging heat with the return air RA in the exhaust heat exchanger 41. The secondary-side refrigerant REF2 is heated by exchanging heat with the heated primary-side refrigerant REF1 in the intermediate heat exchanger 51. Therefore, in FIG. 20, when the secondary-side refrigerant REF2 is heated in the intermediate heat exchanger 51, the enthalpy and pressure of the secondary-side refrigerant REF2 change from point B4 to point B1. In FIG. 20, the section HX4 indicates a section heated by the exhaust heat exchanger 41, and the section HX5 indicates a section heated by the intermediate heat exchanger 51.

SUMMARY

According to the air conditioning system 5 according to the fifth embodiment, efficiency can be improved by combining a ventilation apparatus that recovers heat at an intermediate pressure in an air conditioner equipped with a binary cycle. Further, according to the air conditioning system 5 according to the fifth embodiment, latent heat-sensible heat separation air conditioning of an air conditioner (indoor/outdoor unit) and a heat recovery device (supply/exhaust unit) can be implemented.

The compressor 461 is an example of a seventh compressor, the primary-side refrigerant REF1 is an example of a seventh refrigerant, the primary-side refrigerant pipe 481 is an example of a seventh refrigerant pipe, and the primary-side refrigerant circuit CIR41 is an example of a seventh refrigerant circuit. The compressor 462 is an example of an eighth compressor, the secondary-side refrigerant REF2 is an example of an eighth refrigerant, the secondary-side refrigerant pipe 482 is an example of an eighth refrigerant pipe, and the secondary-side refrigerant circuit CIR42 is an example of an eighth refrigerant circuit. The intermediate heat exchanger 51 is an example of a fourth intermediate heat exchanger.

Although the embodiments have been described above, it will be understood that various modifications of the form and details are possible without departing from the spirit and scope of the claims. Various modifications and improvements are possible, such as combining or replacing with some or all of other embodiments.