Air Conditioning System and Ventilation Apparatus

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.

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

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.

The present disclosure provides an air conditioning system including:

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.

An air conditioning systemaccording to the first embodiment will be described below.is a diagram illustrating a schematic configuration of the air conditioning systemaccording to the first embodiment.is a diagram explaining a primary-side refrigerant circuit CIRand a secondary-side refrigerant circuit CIRin the air conditioning systemaccording to the first embodiment. The air conditioning systemprovides ventilation between the inside IDS and the outside OPS of a building BLD. The air conditioning systemprovides 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 unitis 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 unitis referred to as supply air SA. The air taken in by the exhaust unitfrom the inside IDS of the building BLD is referred to as return air RA. The air discharged by the exhaust unitto the outside OPS of the building BLD is referred to as exhaust air EA.

The air conditioning systemincludes an outdoor unit, an air supply unit, an indoor unit, an exhaust unit, and a heat exchange unit. The air conditioning systemalso includes a compressor, a compressor, an expansion valve, and an expansion valve.

The outdoor unitis provided in the outside OPS of the building BLD. The outdoor unitis what is referred to as an outdoor unit. The outdoor unitexchanges heat between the outside air OA in the outside OPS of the building BLD and the primary-side refrigerant REF. The outdoor unitincludes an outdoor heat exchangerand a fan.

The outdoor heat exchangerexchanges heat between the outside air OA and the primary-side refrigerant REFin the outside OPS of the building BLD. The outdoor heat exchangerincludes a plurality of plate-type fins and a pipe that penetrate the fins and through which the primary-side refrigerant REFflows. By passing the outside air OA between the plurality of plate-type fins, the outdoor heat exchangerexchanges heat between the outside air OA and the primary-side refrigerant REF.

The fanpasses the outside air OA through the outdoor heat exchanger. The fanmay, for example, supply the outside air OA to the outdoor heat exchangeror exhaust the outside air OA that has passed through the outdoor heat exchanger. The outside air OA that has been passed through the outdoor heat exchangerby the fanexchanges heat with the primary-side refrigerant REFflowing through the outdoor heat exchanger. The outside air OA that has exchanged heat with the outdoor heat exchangeris exhausted to the outside OPS of the building BLD. The fanis, for example, an axial flow fan.

The air supply unittakes 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 REF. The air supply unitthen 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 unitincludes an air supply heat exchangerand the fan. 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, is referred to as an air supply path P.

The air supply heat exchangerperforms heat exchange between the outside air OA and the primary-side refrigerant REF. The air supply heat exchangeris provided with a plurality of plate-shaped fins and a pipe that penetrates the fins and through which the primary-side refrigerant REFflows.

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

The fanblows the outside air OA to the air supply heat exchanger. The outside air OA blown to the air supply heat exchangerby the fanexchanges heat with the primary-side refrigerant REFflowing through the air supply heat exchanger. The outside air OA that has undergone heat exchange is blown inside the building BLD as the supply air SA. The fanis, for example, a centrifugal fan or an axial flow fan.

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

The indoor unitis provided in the inside IDS of the building BLD. The indoor unitis what is referred to as an indoor unit. The indoor unitexchanges heat between the air of the inside IDS of the building BLD and the secondary-side refrigerant REF. The indoor unitincludes an indoor heat exchanger.

The indoor heat exchangerexchanges heat between the air of the inside IDS of the building BLD and the secondary-side refrigerant REF. The indoor heat exchangerincludes a plurality of plate-shaped fins and a pipe that penetrate the fins and through which the secondary-side refrigerant REFflows. The indoor heat exchangerexchanges heat between the inside IDS air and the secondary-side refrigerant REFby passing the inside IDS air between the plurality of plate type fins.

The indoor unitmay be provided with a fan. The inside IDS air may be sent to the indoor heat exchangerby the fan provided in the indoor unit, or the inside IDS air passed through the indoor heat exchangermay be exhausted to the inside IDS.

The exhaust unittakes 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 REF, and exhausts the returned air RA after heat exchange to the outside OPS of the building BLD as exhaust air EA. The exhaust unitincludes an exhaust heat exchangerand the fan. 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, is referred to as an exhaust path P.

The exhaust heat exchangerexchanges heat between the return air RA and the secondary-side refrigerant REF. The exhaust heat exchangerincludes 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, heat exchange is performed between the return air RA and the secondary-side refrigerant REFflowing in the pipe of the exhaust heat exchanger.

The fanblows the return air RA to the exhaust heat exchanger. The fanis, for example, a centrifugal fan or an axial flow fan. The return air RA heat exchanged by the exhaust heat exchangeris discharged outdoors as exhaust air EA.

The arrangement of the exhaust heat exchangerand the fanmay be reversed, and the return air RA heat exchanged by the exhaust heat exchangermay be blown outdoors of the building BLD as exhaust air EA by the fan.

The heat exchange unitexchanges heat between the primary-side refrigerant REFand the secondary-side refrigerant REF. The heat exchange unitincludes an intermediate heat exchanger. The intermediate heat exchangeris what is referred to as a cascade heat exchanger. The intermediate heat exchangerexchanges heat between the primary-side refrigerant REFand the secondary-side refrigerant REF.

The compressordischarges the compressed primary-side refrigerant REF. The compressordischarges the compressed secondary-side refrigerant REF. Each of the compressorand compressoris what is referred to as a compressor. Each of the compressorand the compressoris, for example, a turbo compressor or a positive displacement compressor. Each of the compressorand the compressorcan change the direction in which the refrigerant is discharged by providing a selector valve or the like.

The expansion valvedepressurizes the compressed primary-side refrigerant REF. The expansion valvedepressurizes the compressed secondary-side refrigerant REF.

The primary-side refrigerant circuit CIRand the secondary-side refrigerant circuit CIRin the air conditioning systemwill be described below.is a diagram for explaining the primary-side refrigerant circuit CIRand the secondary-side refrigerant circuit CIRin the air conditioning systemaccording to the first embodiment. In, the arrows of the primary-side refrigerant REFand the secondary-side refrigerant REFindicate the direction in which the refrigerant flows during cooling.

The air conditioning systemincludes the primary-side refrigerant circuit CIRand the secondary-side refrigerant circuit CIR. The primary-side refrigerant circuit CIRand the secondary-side refrigerant circuit CIRare thermally connected via the intermediate heat exchanger.

The primary-side refrigerant circuit CIRincludes the compressor, the outdoor heat exchanger, the air supply heat exchanger, the intermediate heat exchanger, and the expansion valveconnected via a primary-side refrigerant pipe. Through the primary-side refrigerant circuit CIR, a primary-side refrigerant REFflows therein via the primary-side refrigerant pipe. The primary-side refrigerant circuit CIRconstitutes a primary-side refrigeration cycle HCdescribed below.

In the primary-side refrigerant circuit CIR, the outdoor heat exchanger, the expansion valve, the intermediate heat exchanger, and the air supply heat exchangerare connected in this order from the compressor, returning to the compressor.

During cooling, in the primary-side refrigerant circuit CIR, the primary-side refrigerant REFcompressed and heated by the compressorflows in order from the compressorto the outdoor heat exchangerand the expansion valve. The primary-side refrigerant REFis depressurized at the expansion valve. The depressurized primary-side refrigerant REFflows in order from the expansion valveto the intermediate heat exchangerand the air supply heat exchanger. The primary-side refrigerant REFthat has passed through the air supply heat exchangerreturns to the compressor.

During heating, in the primary-side refrigerant circuit CIR, the primary-side refrigerant REFthat has been compressed and heated by the compressorflows in order from the compressorto the air supply heat exchanger, the intermediate heat exchanger, and the expansion valve. The primary-side refrigerant REFis depressurized at the expansion valve. The depressurized primary-side refrigerant REFflows from the expansion valveto the outdoor heat exchanger. The primary-side refrigerant REFthat has passed through the outdoor heat exchangerreturns to the compressor.

The secondary-side refrigerant circuit CIRincludes the compressor, the indoor heat exchanger, the exhaust heat exchanger, the intermediate heat exchanger, and the expansion valveconnected by a secondary-side refrigerant pipe. In the secondary-side refrigerant circuit CIR, a secondary-side refrigerant REFflows therein via the secondary-side refrigerant pipe. The secondary-side refrigerant circuit CIRconstitutes a secondary-side refrigeration cycle HC, which will be described below.

In the secondary-side refrigerant circuit CIR, the intermediate heat exchanger, the exhaust heat exchanger, the expansion valve, and the indoor heat exchangerare connected in this order from the compressor, returning to the compressor.

During cooling, in the secondary-side refrigerant circuit CIR, the secondary-side refrigerant REFcompressed and heated by the compressorflows in order from the compressorto the intermediate heat exchanger, the exhaust heat exchanger, and the expansion valve. The secondary-side refrigerant REFis depressurized at the expansion valve. The depressurized secondary-side refrigerant REFflows from the expansion valveto the indoor heat exchanger. The secondary-side refrigerant REFthat has passed through the indoor heat exchangerreturns to the compressor.

During heating, in the secondary-side refrigerant circuit CIR, the secondary-side refrigerant REFthat has been compressed and heated by the compressorflows from the compressorto the indoor heat exchangerand the expansion valvein this order. The secondary-side refrigerant REFis depressurized at the expansion valve. The depressurized secondary-side refrigerant REFflows from the expansion valveto the exhaust heat exchangerand the intermediate heat exchanger. The secondary-side refrigerant REFthat has passed through the intermediate heat exchangerreturns to the compressor.

The primary-side refrigeration cycle HCin the primary-side refrigerant circuit CIRand the secondary-side refrigeration cycle HCin the secondary-side refrigerant circuit CIRwill be described below.is a diagram for explaining the primary-side refrigeration cycle HCand the secondary-side refrigeration cycle HCduring cooling by the air conditioning systemaccording to the first embodiment.is a diagram for explaining the primary-side refrigeration cycle HCand the secondary-side refrigeration cycle HCduring heating by the air conditioning systemaccording to the first embodiment.

are diagrams schematically illustrating the primary-side refrigeration cycle HCand the secondary-side refrigeration cycle HCin an enthalpy-pressure diagram (Mollier diagram).are diagrams for explaining the operation, and the refrigeration cycle is simplified. The horizontal axes ofrespectively indicate enthalpy. The vertical axes ofrespectively indicate pressure.

First, the primary-side refrigeration cycle HCand the secondary-side refrigeration cycle HCof the air conditioning systemaccording to the first embodiment during cooling will be described with reference to.

First, the primary-side refrigeration cycle HCwill be described in order from point A, which indicates the position in the compressorat which the primary-side refrigerant REFis taken in.

During cooling, when the compressorcompresses the primary-side refrigerant REF, the pressure of the primary-side refrigerant REFincreases and the temperature of the primary-side refrigerant REFalso increases. Therefore, in, when the compressorcompresses the primary-side refrigerant REF, the enthalpy and pressure of the primary-side refrigerant REFchange from point Ato point A. Specifically, at points Ato A, the temperature of the primary-side refrigerant REFincreases, the enthalpy increases, and the pressure increases.

Next, the primary-side refrigerant REFis cooled by exchanging heat with outside air OA in the outdoor heat exchanger. Therefore, in, when the primary-side refrigerant REFis cooled in the outdoor heat exchanger, the enthalpy and pressure of the primary-side refrigerant REFchange from point Ato point A, as indicated in the section HX. Specifically, at points Ato A, the pressure is constant, the temperature of the primary-side refrigerant REFdecreases, and the enthalpy decreases.

Next, the pressure of the primary-side refrigerant REFis reduced by being depressurized at the expansion valve. Therefore, in, the enthalpy and pressure of the primary-side refrigerant REFchange from point Ato point Awhen the primary-side refrigerant REFis depressurized at the expansion valve. Specifically, from point Ato point A, the enthalpy of the primary-side refrigerant REFremains constant and the pressure decreases.

Next, the primary-side refrigerant REFis heated by exchanging heat with the heated secondary-side refrigerant REFin the intermediate heat exchanger. The primary-side refrigerant REFis heated by exchanging heat with the outside air OA in the air supply heat exchanger. Therefore, in, when the primary-side refrigerant REFis heated in the intermediate heat exchangerand the air supply heat exchanger, the enthalpy and pressure of the primary-side refrigerant REFchange from point Ato point A. Specifically, from point Ato point A, the pressure is constant, and the temperature of the primary-side refrigerant REFrises, and the enthalpy increases. In, the section HXindicates the section heated by the intermediate heat exchanger, and the section HXindicates the section heated by the air supply heat exchanger.

Next, the secondary-side refrigeration cycle HCwill be described in order starting from point B, which indicates the position in the compressorat which the secondary-side refrigerant REFis taken in.

During cooling, when the compressorcompresses the secondary-side refrigerant REF, the pressure of the secondary-side refrigerant REFincreases and the temperature of the secondary-side refrigerant REFalso increases. Therefore, in, when the compressorcompresses the secondary-side refrigerant REF, the enthalpy and pressure of the secondary-side refrigerant REFchange from point Bto point B. Specifically, from point Bto point B, the temperature of the secondary-side refrigerant REFincreases, the enthalpy increases, and the pressure increases.

Next, the secondary-side refrigerant REFis cooled by exchanging heat with the cooled primary-side refrigerant REFin the intermediate heat exchanger. The secondary-side refrigerant REFis cooled by exchanging heat with the return air RA in the exhaust heat exchanger. Therefore, in, the enthalpy and pressure of the secondary-side refrigerant REFchange from point Bto Bas the secondary-side refrigerant REFis cooled in the intermediate heat exchangerand the exhaust heat exchanger. Specifically, from point Bto point B, the pressure is constant, and the temperature of the secondary-side refrigerant REFdecreases, and the enthalpy decreases. In, the section HXindicates the section cooled by the intermediate heat exchanger, and the section HXindicates the section cooled by the exhaust heat exchanger.

Next, the pressure of the secondary-side refrigerant REFdecreases by being depressurized at the expansion valve. Therefore, in, when the secondary-side refrigerant REFis depressurized at the expansion valve, the enthalpy and pressure of the secondary-side refrigerant REFchange from point Bto point B. Specifically, from point Bto point B, the enthalpy of the secondary-side refrigerant REFremains constant and the pressure decreases.

Next, the secondary-side refrigerant REFis heated by exchanging heat with inside IDS air in the indoor heat exchanger. Therefore, in, when the secondary-side refrigerant REFis heated in the indoor heat exchanger, the enthalpy and pressure of the secondary-side refrigerant REFchange from point Bto point Bas indicated in the section HX. Specifically, from point Bto point B, the pressure remains constant and the temperature of the secondary-side refrigerant REFincreases and the enthalpy increases.