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EP-4741733-A1 - REFRIGERATION CYCLE DEVICE

EP4741733A1EP 4741733 A1EP4741733 A1EP 4741733A1EP-4741733-A1

Abstract

A refrigeration cycle apparatus with which highly efficient operation is possible has been demanded. An air conditioner (100) includes a first refrigerant circuit (110) and a second refrigerant circuit (120). The first refrigerant circuit includes a first compressor (10), a first heat exchanger (40) functioning as a radiator for a refrigerant, a first expansion valve (50), and a second heat exchanger (60) functioning as a heat absorber for the refrigerant. The second refrigerant circuit connects a portion between the first compressor and the first heat exchanger and a portion between the first heat exchanger and the first expansion valve. The second refrigerant circuit includes a second compressor (20). Suction pressure of the first compressor is lower than suction pressure of the second compressor. The first compressor is a scroll compressor, and the second compressor is a rotary compressor. Alternatively, the first compressor is a scroll compressor having a first design compression ratio, and the second compressor is a scroll compressor having a second design compression ratio smaller than the first design compression ratio.

Inventors

  • KABASHIMA, Nobutaka
  • YAMAGUCHI, MASAKI

Assignees

  • DAIKIN INDUSTRIES, LTD.

Dates

Publication Date
20260513
Application Date
20250910

Claims (12)

  1. A refrigeration cycle apparatus (100, 200) comprising: a first refrigerant circuit (110, 200a) including a first compressor (10, 210), a radiator (40, 240), a first expansion valve (50, 250a), and a heat absorber (60, 260a); and a second refrigerant circuit (120, 200b) that connects a portion between the first compressor and the radiator and a portion between the radiator and the first expansion valve, the second refrigerant circuit including a second compressor (20, 220), suction pressure of the first compressor being lower than suction pressure of the second compressor, wherein the first compressor is a scroll compressor, and the second compressor is a rotary compressor or the first compressor is a scroll compressor having a first design compression ratio, and the second compressor is a scroll compressor having a second design compression ratio smaller than the first design compression ratio.
  2. The refrigeration cycle apparatus (100) according to claim 1, wherein the second refrigerant circuit (120) further includes a second expansion valve (80) and an economizer heat exchanger (70) disposed between the radiator (40) and the heat absorber (60), the economizer heat exchanger is configured to exchange heat between the refrigerant that flows out of the radiator, is branched to the second refrigerant circuit at a branch portion (82), and is decompressed by the second expansion valve and the refrigerant that flows out of the radiator, and the refrigerant decompressed by the second expansion valve and passing through the economizer heat exchanger is sucked into the second compressor (20).
  3. The refrigeration cycle apparatus according to claim 2, wherein the branch portion is disposed between the radiator and the economizer heat exchanger.
  4. The refrigeration cycle apparatus (100) according to claim 1, wherein the first refrigerant circuit (110) further includes a second expansion valve (84), the second refrigerant circuit (120) further includes a refrigerant vessel (72) that is configured to separate gas and liquid, the refrigerant vessel being disposed between the radiator (40) and the heat absorber (60), into which the refrigerant flowing out of the radiator and decompressed to be brought into a two-phase state by the second expansion valve flows, and the gas refrigerant separated in the refrigerant vessel is sucked into the second compressor (20).
  5. The refrigeration cycle apparatus according to claim 4, wherein the second refrigerant circuit further includes a heat exchanger (70b) the heat exchanger is arranged to exchange heat between the refrigerant flowing out of the radiator toward the second expansion valve and the gas refrigerant separated in the refrigerant vessel.
  6. The refrigeration cycle apparatus according to any one of claims 2 to 5, wherein the second compressor is a rotary compressor, and, in a case where a load is at least equal to or lower than 47%, a number of rotations of the first compressor (10) is greater than a number of rotations of the second compressor.
  7. The refrigeration cycle apparatus according to claim 6, wherein, in a case where the load is at least equal to or lower than 74%, the number of rotations of the first compressor is greater than the number of rotations of the second compressor.
  8. The refrigeration cycle apparatus (100, 200) according to any one of claims 1 to 7, wherein the refrigerant filled in the first refrigerant circuit (110, 200a) and the second refrigerant circuit (120, 200b) contains CO 2 at least partially in its components.
  9. The refrigeration cycle apparatus according to any one of claims 1 to 7 wherein the second compressor is a rotary compressor, and the refrigerant filled in the first refrigerant circuit (110) and the second refrigerant circuit is CO 2 .
  10. The refrigeration cycle apparatus according to claim 9, wherein a ratio of displacement of the second compressor with respect to displacement of the first compressor (10) is determined so that, in a case where a load is 47%, a number of rotations of the second compressor is greater than a minimum number of rotations at which continuous operation is possible.
  11. The refrigeration cycle apparatus according to claim 9 or 10, wherein a ratio of displacement of the second compressor with respect to displacement of the first compressor (10) is determined so that, in a case where a load is 100%, a number of rotations of the second compressor is smaller than a maximum number of rotations at which continuous operation is possible.
  12. The refrigeration cycle apparatus (100) according to any one of claims 1 to 11, further comprising a bypass flow path (92) connecting a discharge side of the second compressor (20) in the second refrigerant circuit (120) or a portion between a discharge port of the first compressor (10) and the radiator (40) in the first refrigerant circuit (110) and a suction side of the second compressor in the second refrigerant circuit; a valve (94) disposed in the bypass flow path; and a control unit (8) configured to control operation of the valve, wherein the control unit is configured to open the valve when the second compressor is to be stopped.

Description

TECHNICAL FIELD The present disclosure relates to a refrigeration cycle apparatus. BACKGROUND ART Conventionally, there may be cases where such a configuration has been adopted, depending on application of a refrigeration cycle apparatus or a type of a refrigerant used, for example, that, similar to a refrigeration cycle apparatus according to PTL 1 (Japanese Unexamined Patent Application Publication No. 2005-49087), a plurality of compressors are provided in a refrigerant circuit in the refrigeration cycle apparatus, the compressors are each caused to suck the refrigerant that varies in pressure, and the refrigerant compressed by each of the plurality of compressors is discharged to a single refrigerant flow path. SUMMARY OF INVENTION <Technical Problem> Although, in such a refrigeration cycle apparatus as described above, efficient operation may be difficult to achieve depending on compressors selected, such a configuration of a refrigeration cycle apparatus with which highly efficient operation is possible is not disclosed in PTL 1 (Japanese Unexamined Patent Application Publication No. 2005-49087). <Solution to Problem> A refrigeration cycle apparatus according to a first aspect comprises a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit includes a first compressor, a radiator, a first expansion valve, and a heat absorber. The second refrigerant circuit connects a portion between the first compressor and the radiator and a portion between the radiator and the first expansion valve. The second refrigerant circuit includes a second compressor. Suction pressure of the first compressor is lower than suction pressure of the second compressor. The first compressor is a scroll compressor, and the second compressor is a rotary compressor. Alternatively, the first compressor is a scroll compressor having a first design compression ratio, and the second compressor is a scroll compressor having a second design compression ratio smaller than the first design compression ratio. In the refrigeration cycle apparatus according to the first aspect, the second refrigerant circuit is connected to the first refrigerant circuit at the portion between the first compressor and the radiator. Therefore, the first compressor and the second compressor are identical to each other in discharge pressure. Furthermore, in the refrigeration cycle apparatus according to the first aspect, the suction pressure of the first compressor is lower than the suction pressure of the second compressor. Therefore, in the refrigeration cycle apparatus according to the first aspect, the compression ratio of the first compressor becomes greater than the compressor of the second compressor. Using a scroll compressor that is high in efficiency in a region where the compression ratio is high as the first compressor and a rotary compressor that is high in efficiency in a region where the compression ratio is low as the second compressor makes it possible to make the refrigeration cycle apparatus highly efficient. Also, in a case where a scroll compressor that is great in design compression ratio is used as the first compressor and a scroll compressor that is small in design compression ratio is used as the second compressor, it is possible to operate both the compressors in efficient regions, making it possible to make the refrigeration cycle apparatus highly efficient. A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, the second refrigerant circuit further includes a second expansion valve and an economizer heat exchanger disposed between the radiator and the heat absorber. The economizer heat exchanger is configured to exchange heat between the refrigerant that flows out of the radiator, is branched to the second refrigerant circuit at a branch portion, and is decompressed by the second expansion valve and the refrigerant that flows out of the radiator. The refrigerant decompressed by the second expansion valve and passing through the economizer heat exchanger is sucked into the second compressor. In the refrigeration cycle apparatus according to the second aspect, as the refrigerant that has passed through the economizer heat exchanger is compressed by the second compressor, it is possible to achieve improvements in capability and performance. A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the second aspect, the branch portion is disposed between the radiator and the economizer heat exchanger. In the refrigeration cycle apparatus according to the third aspect, the refrigerant that has flowed out of the radiator is partially branched to the second refrigerant circuit and flows toward the economizer heat exchanger via the second expansion valve, and rest of the refrigerant flows toward the first expansion valve via the economizer heat exchanger. Therefore, with the refriger