EP-4317845-B1 - REFRIGERATION CYCLE DEVICE

EP4317845B1EP 4317845 B1EP4317845 B1EP 4317845B1EP-4317845-B1

Inventors

YOSHIMI, ATSUSHI
YAMADA, TAKURO
KUMAKURA, EIJI
IWATA, IKUHIRO
KAJI, RYUHEI
MIYAZAKI, Takeru
UEDA, HIROKI
TANAKA, MASAKI
NAKAYAMA, MASAKI

Dates

Publication Date: 20260513
Application Date: 20220331

Claims (12)

A refrigeration cycle apparatus (1) comprising a first refrigerant circuit (10) comprising a first refrigerant and having a use heat exchanger (13), a switching mechanism (12), a first compressor (11), a heat-source heat exchanger (17), and a first outdoor heat exchanger (18), and a second refrigerant circuit (20) comprising a second refrigerant and having the heat-source heat exchanger (17), a second compressor (21), and a second outdoor heat exchanger (23), wherein the switching mechanism (12) is configured to enable the refrigeration cycle apparatus (1) to perform: a heating operation by performing a two-stage refrigeration cycle, wherein the first refrigerant circuit (10) performs a refrigeration cycle such that the use heat exchanger (13) functions as a condenser of the first refrigerant and the heat source heat exchanger (17) functions as an evaporator of the first refrigerant and the first outdoor heat exchanger (18) is not in use, and the second refrigerant circuit (20) performs a refrigeration cycle such that the heat-source heat exchanger (17) functions as a radiator of the second refrigerant and the second outdoor heat exchanger (23) functions as an evaporator of the second refrigerant, and a cooling operation by performing a single-stage refrigeration cycle, wherein the first refrigerant circuit (10) performs a refrigeration cycle such that the use heat exchanger (13) functions as an evaporator of the first refrigerant and the first outdoor heat exchanger (18) functions as a condenser of the first refrigerant and the heat-source heat exchanger (17) is not in use; and the second refrigerant circuit (20) does not perform a refrigeration cycle; and the first refrigerant has 1 MPa or less at 30°C and the second refrigerant has 1.5 MPa or more at 30°C.
The refrigeration cycle apparatus according to claim 1, wherein the heat-source heat exchanger (17) is a cascade heat exchanger (17) including a first cascade flow path (17a) through which the first refrigerant flows during the heating operation and a second cascade flow path (17b) that is independent of the first cascade flow path and through which the second refrigerant flows during the heating operation, the cascade heat exchanger (17) being configured to exchange heat between the first refrigerant and the second refrigerant.
The refrigeration cycle apparatus according to claim 2, wherein during the heating operation, the first refrigerant evaporates when passing through the first cascade flow path (17a), and the second refrigerant radiates heat when passing through the second cascade flow path (17b).
A refrigeration cycle apparatus (1a, 1b, 1c) comprising a first refrigerant circuit (10) comprising a first refrigerant and having a use heat exchanger (13), a switching mechanism (12), a first compressor (11), a heat-source heat exchanger (17), and a first outdoor heat exchanger (18), and a second refrigerant circuit (20) comprising a second refrigerant and having the heat-source heat exchanger (17), the use heat exchanger (13), a second compressor (21), and a second outdoor heat exchanger (23), wherein the refrigeration cycle apparatus is configured to perform: a heating operation by performing a two-stage refrigeration cycle, wherein the first refrigerant circuit (10) performs a refrigeration cycle such that the use heat exchanger (13) functions as a condenser of the first refrigerant and the heat source heat exchanger (17) functions as an evaporator of the first refrigerant and the first outdoor heat exchanger (18) is not in use, and the second refrigerant circuit (20) performs a refrigeration cycle such that the heat-source heat exchanger (17) functions as a radiator of the second refrigerant and the second outdoor heat exchanger (23) functions as an evaporator of the second refrigerant, and a cooling operation by performing a two-stage refrigeration cycle, wherein the first refrigerant circuit (10) performs a refrigeration cycle such that the first outdoor heat exchanger (18) functions as a condenser of the first refrigerant and the heat-source heat exchanger (17) functions as an evaporator of the first refrigerant, and the second refrigerant circuit (20) performs a refrigeration cycle such that the heat-source heat exchanger (17) functions as a radiator of the second refrigerant and the use heat exchanger (13) functions as an evaporator of the second refrigerant and the second outdoor heat exchanger (23) is not in use; and the first refrigerant has 1 MPa or less at 30°C and the second refrigerant has 1.5 MPa or more at 30°C.
The refrigeration cycle apparatus according to claim 4, wherein the heat-source heat exchanger (17) is a cascade heat exchanger (17) including a first cascade flow path (17a) through which the first refrigerant flows and a second cascade flow path (17b) that is independent of the first cascade flow path and through which the second refrigerant flows, the cascade heat exchanger (17) being configured to exchange heat between the first refrigerant and the second refrigerant.
The refrigeration cycle apparatus according to claim 5, wherein the use heat exchanger (13) includes a first use flow path (13a) through which the first refrigerant flows and a second use flow path (13b) that is independent of the first use flow path and through which the second refrigerant flows.
The refrigeration cycle apparatus according to claim 6, wherein during the heating operation, the first refrigerant evaporates when passing through the first cascade flow path (17a), the second refrigerant radiates heat when passing through the second cascade flow path (17b), and the first refrigerant radiates heat when passing through the first use flow path (13a).
The refrigeration cycle apparatus according to claim 6 or 7, wherein during the cooling operation, the first refrigerant evaporates when passing through the first cascade flow path (17a), the second refrigerant radiates heat when passing through the second cascade flow path (17b), and the second refrigerant evaporates when passing through the second use flow path (13b).
The refrigeration cycle apparatus according to any one of claims 6 to 8, wherein during the cooling operation, the first refrigerant evaporates when passing through the first use flow path (13a), and the second refrigerant evaporates when passing through the second use flow path (13b).
The refrigeration cycle apparatus according to any one of claims 6 to 9, wherein during the heating operation, the first refrigerant radiates heat when passing through the first use flow path (13a), and the second refrigerant radiates heat when passing through the second use flow path (13b).
The refrigeration cycle apparatus according to any one of claims 1 to 10, wherein the first refrigerant includes at least one of R1234yf or R1234ze.
The refrigeration cycle apparatus according to any one of claims 1 to 11, wherein the second refrigerant includes carbon dioxide.

Description

TECHNICAL FIELD The present invention relates to a refrigeration cycle apparatus. BACKGROUND ART To date, refrigeration cycle apparatuses have been proposed that use refrigerants with low global warming potential (GWP), taking into account the global environment. For example, in a refrigeration cycle apparatus described in JP 2015-197254, it is proposed to fill a refrigerant circuit with a working fluid having a GWP equal to or less than a predetermined value. CN 108 759 144 A discloses a cascading ultralow-temperature air source heat pump unit comprising a water-side heat exchanger, a first refrigerant circuit and a second refrigerant circuit and a cascade heat exchanger. The first refrigerant circuit comprises a low-temperature compressor, a low-temperature four-way reversing valve, an air-side heat exchanger, the water-side heat exchanger and the cascade heat exchanger. The second refrigerant circuit comprises a high-temperature compressor, the water-side heat exchanger and the cascade heat exchanger. The heat pump is configured such that the first refrigerant circuit and the second refrigerant circuit can be operated in a two-stage heating mode, and such that the first refrigerant circuit can be operated in a single-stage heating mode or in a single-stage cooling mode. SUMMARY OF INVENTION TECHNICAL PROBLEM The refrigerants with low GWP described above include a low-pressure refrigerant used at a relatively low refrigerant pressure. Such a low-pressure refrigerant has low heat transfer capacity, and a sufficient amount of circulation of the refrigerant is difficult to secure during a heating operation, with the tendency that the heating operation is difficult to perform or the COP (Coefficient Of Performance) is low during the heating operation. To address this, a two-stage refrigeration cycle in which a carbon dioxide refrigerant serving as a high-pressure refrigerant with low GWP is used as a heat-source-side refrigerant and a low-pressure refrigerant is used as a use-side refrigerant may be used to secure heating operation capacity. However, even in this case, the critical pressure of the carbon dioxide refrigerant on the heat-source side is exceeded during a cooling operation, and the COP is low during the cooling operation. Accordingly, it is desirable to provide a refrigeration cycle apparatus capable of efficiently performing a cooling operation and a heating operation using a high-pressure refrigerant and a low-pressure refrigerant. SOLUTION TO PROBLEM The claimed invention is defined by the independent claims 1 and 4. Optional features are described in the dependent claims. In a first aspect of the claimed invention, a two-stage refrigeration cycle is performed during the heating operation, the two-stage refrigeration cycle including a use-side refrigeration cycle using a first refrigerant that is a low-pressure refrigerant having 1 MPa or less at 30°C and a heat-source-side refrigeration cycle using a second refrigerant that is a high-pressure refrigerant having 1.5 MPa or more at 30°C. Thus, it is easy to secure heating capacity while achieving a high COP. In this refrigeration cycle apparatus, furthermore, a single-stage refrigeration cycle using the first refrigerant, which is a low-pressure refrigerant having 1 MPa or less at 30°C, is performed during the cooling operation. Thus, it is possible to perform the two-stage refrigeration cycle using the second refrigerant in the heat-source-side refrigeration cycle, without causing a reduction in COP due to the second refrigerant exceeding a critical pressure. Accordingly, the cooling operation and the heating operation can be efficiently performed using a high-pressure refrigerant and a low-pressure refrigerant. In the use heat exchanger, the first refrigerant evaporates during the cooling operation. In the first outdoor heat exchanger, the first refrigerant radiates heat during the cooling operation. In the first outdoor heat exchanger, the first refrigerant may condense during the cooling operation. The first outdoor heat exchanger is not limited. For example, the refrigerant flowing through the first outdoor heat exchanger may exchange heat with air. In this refrigeration cycle apparatus, the cooling operation can be efficiently performed by using an outdoor heat source. In the second outdoor heat exchanger, the second refrigerant evaporates during the heating operation. The second outdoor heat exchanger is not limited. For example, the refrigerant flowing through the second outdoor heat exchanger may exchange heat with air. In this refrigeration cycle apparatus, the heating operation can be efficiently performed by using an outdoor heat source. A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, including a cascade heat exchanger. The cascade heat exchanger includes a first cascade flow path and a second cascade flow path. The first cascade flow path is a flow pat