EP4177539A1

EP4177539A1 - Refrigeration device

Info

Publication number: EP4177539A1
Application number: EP21838192.9A
Authority: EP
Inventors: Shun OHKUBO; Tatsumi Tsuchiya; Tsubasa NAKAUE; Takurou Yamada; Satoshi Tokuno
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2020-07-06
Filing date: 2021-07-06
Publication date: 2023-05-10
Also published as: JP2022125358A; CN115885139A; JP7216151B2; JP2022014455A; EP4177539A4; US20230135967A1; WO2022009898A1

Abstract

An object is to provide a novel multi-stage refrigeration apparatus. The object is achieved by a refrigeration apparatus comprising a user-side heat transfer cycle that includes a user-side compressor, a user-side heat exchanger, a user-side pressure-reducing device, and a user-side cascade heat exchanger, and that circulates a user-side refrigerant; a heat-source-side heat transfer cycle that includes a heat-source-side compressor, a heat-source-side heat exchanger, a heat-source-side pressure-reducing device, and a heat-source-side cascade heat exchanger, and that circulates a heat-source-side refrigerant; a cascade heat exchanger configured to exchange heat between the user-side refrigerant of a user-side condenser and the heat-source-side refrigerant of a heat-source-side evaporator; and a control device, the user-side refrigerant having a boiling point of -30°C or more and 25°C or less, and the heat-source-side refrigerant having a boiling point of -55°C or more and less than -30°C.

Description

Technical Field

The present disclosure relates to a refrigeration apparatus.

Background Art

Two-stage refrigeration apparatuses, which include a two-stage refrigerant cycle composed of a user-side heat transfer cycle and a heat-source-side heat transfer cycle, have been proposed (Patent Literature 1 and Patent Literature 2).

Citation List

Patent Literature

PTL 1: WO2015/140872
PTL 2: WO2015/140873

Summary of Invention

Technical Problem

An object of the present disclosure is to provide a novel multi-stage refrigeration apparatus.

Solution to Problem

Item

1.

A refrigeration apparatus comprising:

a user-side heat transfer cycle configured to circulate a user-side refrigerant;
a heat-source-side heat transfer cycle configured to circulate a heat-source-side refrigerant; and
a cascade heat exchanger configured to exchange heat between the user-side refrigerant and the heat-source-side refrigerant,
the user-side refrigerant having a boiling point of -30°C or more and 25°C or less, and the heat-source-side refrigerant having a boiling point of -55°C or more and less than -30°C.

Item 2.

The refrigeration apparatus according to Item 1, wherein the heat-source-side heat transfer cycle is a vapor compression refrigeration cycle comprising a heat-source-side compressor, a heat-source-side heat exchanger, a heat-source-side pressure-reducing device, and a heat-source-side cascade heat exchanger.

Item 3.

The refrigeration apparatus according to Item 1 or 2, wherein the user-side heat transfer cycle is a vapor compression refrigeration cycle comprising a user-side compressor, a user-side heat exchanger, a user-side pressure-reducing device, and a user-side cascade heat exchanger.

Item 4.

The refrigeration apparatus according to Item 1 or 2, wherein the user-side heat transfer cycle is a heat transfer cycle comprising a pump, a user-side heat exchanger, and a user-side cascade heat exchanger.

Item 5.

The refrigeration apparatus according to any one of Items 1 to 4, wherein flow directions of the heat-source-side refrigerant and the user-side refrigerant are in countercurrent flow in the cascade heat exchanger.

Item 6.

The refrigeration apparatus according to any one of Items 1 to 5, wherein the heat-source-side refrigerant has a burning velocity of 10 cm/s or less, and the user-side refrigerant has a burning velocity of 3 cm/s or less.

Item 7.

The refrigeration apparatus according to any one of Items 1 to 6, wherein the heat-source-side refrigerant is classified as Class 2L by ASHRAE, and the user-side refrigerant is classified as Class A1 by ASHRAE.

Item 8.

The refrigeration apparatus according to any one of Items 1 to 5, wherein the heat-source-side refrigerant comprises HFO-1123 and/or HFO-1132.

Item 9.

The refrigeration apparatus according to any one of Items 1 to 7, wherein the heat-source-side refrigerant is R32, R452B, or R454B, and the user-side refrigerant is at least one member selected from the group consisting of R513A, R515A, R515B, R1224, R1234yf, R1234ze, R1233, and R1336.

Item 10.

The refrigeration apparatus according to any one of Items 1 to 8, wherein the heat-source-side refrigerant comprises HFO-1132, and the user-side refrigerant is at least one member selected from the group consisting of R513A, R515A, R515B, R471A, R1224, R1234yf, R1234ze, R1233, and R1336.

Item 11.

The refrigeration apparatus according to any one of Items 1 to 10, which is an air-conditioning system, a refrigerator, a freezer, a water cooler, an ice maker, a refrigerated showcase, a freezing showcase, a freezing and refrigerating unit, a refrigerating machine for freezing and refrigerating warehouses, an air-conditioning system for vehicles, a turbo refrigerating machine, or a screw refrigerating machine.

Item 12.

The refrigeration apparatus according to any one of Items 1 to 10, which is a household air-conditioning system, an air-conditioning system for business use, an industrial air-conditioning system, or a multi-split air-conditioning system for buildings.

Advantageous Effects of Invention

The present disclosure provides a novel multi-stage refrigeration apparatus that allows the safe use of a refrigerant with a low boiling point, high pressure, high density, and high refrigerating capacity.

Brief Description of Drawings

Fig. 1 is a view for illustrating a configuration of the refrigeration apparatus of the present disclosure.
Fig. 2 is a view for illustrating a configuration of the refrigeration apparatus of the present disclosure.

Description of Embodiments

The refrigeration apparatus of the present disclosure comprises:

The heat source side refers to the outdoor unit side and is also referred to as "the high-stage side," "the high-temperature side," or "the primary side." From the viewpoint of improving performance, it is preferable to use a refrigerant with excellent refrigerant characteristics on the heat source side. The user side refers to the indoor unit side and is also referred to as "the low-stage side," "the load side," "the low-temperature side," or "the secondary side." From the viewpoint of cooling people and objects directly, it is preferable to use a highly safe refrigerant on the user side.
The refrigeration apparatus of the present disclosure is a multi-stage refrigeration apparatus that comprises at least a two-stage heat transfer cycle including a user-side heat transfer cycle (load-side heat medium circuit) and a heat-source-side heat medium circuit. The refrigeration apparatus of the present disclosure may comprise three or more heat transfer cycles.
As described later, in cooling operation, the cascade heat exchanger includes a heat-source-side cascade heat exchanger and a user-side cascade heat exchanger, and performs heat exchange. Specifically, in cooling operation, the refrigerant condenses in the user-side cascade heat exchanger, and the refrigerant evaporates in the heat-source-side cascade heat exchanger; thus, heat is transferred from the user side to the heat source side.
The user-side heat transfer cycle circulates the user-side refrigerant. The user-side heat transfer cycle may be a vapor compression refrigeration cycle. The user-side refrigeration cycle that is a vapor compression refrigeration cycle includes a user-side compressor, a user-side heat exchanger, a user-side pressure-reducing device, and a user-side cascade heat exchanger.
The user-side heat transfer cycle may also be a pump heat transfer cycle. The user-side heat transfer cycle that is a pump heat transfer cycle includes a pump, a user-side heat exchanger, and a user-side cascade heat exchanger.
For example, as shown in Fig. 1, an expansion valve 13 or the like can be used as the user-side pressure-reducing device. Alternatively, another pressure-reducing device, such as a capillary tube, can be used as the user-side pressure-reducing device. In addition, the user-side heat exchanger can also be used as a cold source.
For example, when the amount of refrigerant required for the user-side heat transfer cycle significantly varies with changes in operating conditions, a liquid receiver 15 may be provided in a pipe communicating between a user-side cascade heat exchanger 12 and the user-side expansion valve 13, as shown in, for example, Fig. 2.
It is preferred that the user-side heat transfer cycle includes a user-side high-pressure detection means for detecting the high pressure of the user-side heat transfer cycle and a user-side low-pressure detection means for detecting the low pressure of the user-side heat transfer cycle. It is also preferred that the user-side heat transfer cycle includes a user-side discharge temperature detection means for detecting the temperature of the user-side refrigerant discharged from the user-side compressor.
The user-side high-pressure detection means and the user-side low-pressure detection means are means for substantially detecting pressure. That is, the user-side high-pressure detection means and the user-side low-pressure detection means may detect the pressure of the user-side refrigerant itself or may detect other physical quantities that can be converted into the pressure of the user-side refrigerant.
The user-side discharge temperature detection means is a means for substantially detecting temperature. That is, the user-side discharge temperature detection means may detect the discharge temperature of the user-side refrigerant itself or may detect other physical quantities that can be converted into the discharge temperature of the user-side refrigerant.
For example, as shown in Fig. 1, a user-side heat transfer cycle 10 includes a user-side high-pressure sensor 21 as a user-side high-pressure detection means, a user-side low-pressure sensor 22 as a user-side low-pressure detection means, and a user-side discharge temperature sensor 23 as a user-side discharge temperature detection means. The user-side high-pressure sensor 21 is preferably provided in a pipe communicating between the user-side cascade heat exchanger 12 and the user-side expansion valve 13. The user-side low-pressure sensor 22 is preferably provided in a pipe communicating between a user-side heat exchanger 14 and a user-side compressor 11. The user-side discharge temperature sensor 23 is preferably provided in a pipe communicating between the user-side compressor 11 and the user-side condenser 12. The user-side heat transfer cycle need not include some or all of these sensors if they are not needed.
The refrigeration apparatus of the present disclosure may further include a control device. A detection signal from the user-side high-pressure detection means, a detection signal from the user-side low-pressure detection means, and a detection signal from the user-side discharge temperature detection means are input to the control device. The control device controls the overall operation of the refrigeration apparatus of the present disclosure. The control device may be partially or entirely composed of, for example, a microcomputer, a microprocessor unit, or the like; updateable software such as firmware; or a program module or the like that is executed by a command from a CPU or the like.
The user-side refrigerant has a boiling point of -30°C or more and 25°C or less.
The heat-source-side heat transfer cycle circulates the heat-source-side refrigerant. The heat-source-side heat transfer cycle is preferably a vapor compression refrigeration cycle. The heat-source-side refrigeration cycle that is a vapor compression refrigeration cycle includes a heat-source-side compressor, a heat-source-side heat exchanger, a heat-source-side pressure-reducing device, and a heat-source-side cascade heat exchanger.
The heat-source-side compressor is of a variable capacity type. An expansion valve or the like can be used as the heat-source-side pressure-reducing device. Alternatively, another pressure-reducing device, such as a capillary tube, can be used as the heat-source-side pressure-reducing device.
The heat-source-side refrigerant has a boiling point of -55°C or more and less than -30°C.
In cooling operation, a user-side condenser and a heat-source-side evaporator are incorporated in the cascade heat exchanger. When a non-azeotropic refrigerant mixture is used, heat exchange is performed between the user-side refrigerant in the user-side condenser and the heat-source-side refrigerant in the heat-source-side evaporator in the cascade heat exchanger. From the viewpoint of preventing a decrease in heat exchange efficiency due to the temperature glide, it is preferred that the flow directions of the heat-source-side refrigerant and the user-side refrigerant are in countercurrent flow in the cascade heat exchanger.
In heating operation, a user-side evaporator and a heat-source-side condenser are incorporated in the cascade heat exchanger. When a non-azeotropic refrigerant mixture is used, heat exchange is performed between the user-side refrigerant in the user-side evaporator and the heat-source-side refrigerant in the heat-source-side condenser in the cascade heat exchanger. From the viewpoint of preventing a decrease in heat exchange efficiency due to the temperature glide, it is preferred that the flow directions of the heat-source-side refrigerant and the user-side refrigerant are in countercurrent flow in the cascade heat exchanger.
According to the present disclosure, by using a refrigerant with a relatively high density and good performance that has a boiling point of -55°C or more and less than -30°C as the heat-source-side refrigerant, the efficiency of the refrigeration cycles can be maintained within a preferable range, and a refrigerant having a boiling point of -30°C or more and 25°C or less can be used as the user-side refrigerant. Thus, according to the present disclosure, use of a refrigerant with high performance on the heat source side ensures the performance of all cycles within a desirable range without using a refrigerant with a comparable level of performance on the user side. Some refrigerants have boiling points of -30°C or more and 25°C or less, but are excellent in terms of low GWP or low flammability. In the present disclosure, such refrigerants can also be suitably used.
According to the present disclosure, since such a refrigerant excellent in terms of low GWP can be used as the user-side refrigerant, it may be possible to reduce the total GWP of the refrigerants used while maintaining the performance of the entire apparatus. In this respect, the heat-source-side refrigerant preferably has a GWP of 750 or less, more preferably 500 or less, even more preferably 300 or less, and most preferably 150 or less; and the user-side refrigerant preferably has a GWP or 750 or less, more preferably 500 or less, even more preferably 300 or less, and most preferably 150 or less.
Alternatively, since a refrigerant excellent in terms of low flammability as described above can be used as the user-side refrigerant, the risk of harm to people from fire in the event of refrigerant leakage may be further reduced while maintaining the performance of the entire apparatus, by placing the user-side heat transfer cycle in an area in which harm to people is likely to occur. From the viewpoint that a safer refrigerant can be used on the user side, on which harm to people may be caused, the heat-source-side refrigerant preferably has a burning velocity of 10 cm/s or less, more preferably 9 cm/s or less, even more preferably 8 cm/s or less, and most preferably 7 cm/s or less; and the user-side refrigerant preferably has a burning velocity of 5 cm/s or less, more preferably 3 cm/s or less, even more preferably 2 cm/s or less, and most preferably 1.5 cm/s or less.
To make the refrigeration apparatus of the present disclosure suitable for practical use, it is preferable to use a refrigerant with a boiling point of 25°C or less as the user-side refrigerant because its saturation vapor pressure can be made equal to or higher than atmospheric pressure. In this respect, the saturation pressure of the user-side refrigerant at 25°C is preferably 0.0 MPaG or more, more preferably 0.01 MPaG or more, even more preferably 0.03 MPaG or more, and most preferably 0.05 MPaG or more; and the saturation pressure of the user-side refrigerant at 25°C is preferably 5 MPaG or less, more preferably 4 MPaG or less, even more preferably 3 MPaG or less, and most preferably 2 MPaG or less.
To make the refrigeration apparatus of the present disclosure suitable for practical use, a refrigerant with a boiling point of -30°C or more can be used as the user-side refrigerant to maintain its pressure at a level that does not exceed the withstanding pressure limit of the pipe. In this respect, as the user-side refrigerant, it is preferable to use a refrigerant with a boiling point of -30°C or more, more preferable to use a refrigerant with a boiling point of -25°C or more, and even more preferable to use a refrigerant with a boiling point of -20°C or more.
From the viewpoint of reducing the impact on the global environment due to power consumption during use of the refrigeration cycles, the COP of the heat-source-side refrigerant is preferably 95% or more, more preferably 100% or more, even more preferably 101% or more, and still even more preferably 1020 or more, compared with that of R410A.
From the viewpoint of reducing the impact of equipment manufacturing on the global environment by reducing the equipment size, the refrigerating capacity of the heat-source-side refrigerant is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, still even more preferably 90% or more, and most preferably 100% or more, compared with that of R410A.
To reduce the risk of harm to people from fire in the event of refrigerant leakage, examples of the combination of the heat-source-side refrigerant and the user-side refrigerant include a combination of a heat-source-side refrigerant having a burning velocity of 10 cm/s or less and a user-side refrigerant having a burning velocity of 3 cm/s or less. Examples of the combination of the heat-source-side refrigerant and the user-side refrigerant in the above case also include a combination of a heat-source-side refrigerant classified as Class 2L by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and a user-side refrigerant classified as Class A1 by ASHRAE.
When the heat-source-side refrigerant consists essentially of a single compound, examples of the heat-source-side refrigerant include HFO-1123, HFO-1132, R32, and the like. When the heat-source-side refrigerant is a mixture of a plurality of compounds, examples of the heat-source-side refrigerant include a mixture of at least two members selected from the group consisting of HFO-1123, HFO-1132, R1234yf, and R32; R452B; R454B; and the like. R452B is a mixture of R32, R125, and R1234yf (R32:R125:R1234yf (mass ratio) = 67:7:26), and R454B is a mixture of R32 and R1234yf (R32:R1234yf (mass ratio) = 68.9:31.1).

Specific examples of the heat-source-side refrigerant and the user-side refrigerant include the combinations shown in the table below.

Table 1

Heat-source-side refrigerant	User-side refrigerant
R410A	R513A
R410A	R515B
R410A	R1234ze(E)
R410A	R1336mcy
R410A	R1336mzz(E)
R410A	R1224yd(Z)
R32	R513A
R32	R515B
R32	R1234ze(E)
R32	R1336mcy
R32	R1336mzz(E)
R32	R1224yd(Z)
R454B	R513A
R454B	R515B
R454B	R1234ze(E)
R454B	R1336mcy
R454B	R1336mzz(E)
R454B	R1224yd(Z)
R452B	R513A
R452B	R515B
R452B	R1234ze(E)
R452B	R1336mcy
R452B	R1336mzz(E)
R452B	R1224yd(Z)
R454C	R513A
R454C	R515B
R454C	R1234ze(E)
R454C	R1336mcy
R454C	R1336mzz(E)
R454C	R1224yd(Z)

A mixture with HFO-1132 may contain at least one member selected from the group consisting of HFC32, HF01234yf, HF01234ze(E), and CO₂.
In the above, HFO-1132 is preferably HFO-1132(E), HFO-1132(z), or HFO-1132a, and most preferably HFO-1132(E). A mixture with HFO-1123 may contain at least one member selected from the group consisting of HFC32, HF01234yf, HF01234ze(E), and CO₂.
Examples of the combination of the heat-source-side refrigerant and the user-side refrigerant include a combination of a heat-source-side refrigerant that is R32, R452B, or R454B, and a user-side refrigerant that is at least one member selected from the group consisting of R513A, R515A, R515B, R1224, R1234yf, R1234ze, R1233, and R1336. This combination is preferred in that the capacity of the refrigerant used on the heat source side is high.
Examples of the combination of the heat-source-side refrigerant and the user-side refrigerant include a combination of a heat-source-side refrigerant containing HFO-1132 and a user-side refrigerant that is at least one member selected from the group consisting of R513A, R515A, R515B, R471A, R1224, R1234yf, R1234ze, R1233, and R1336. This combination is preferred in that the GWP (t-CO₂) of the entire system can be reduced.
In the present specification, HFO-1132 refers to HFO-1132a, HFO-1132(E), or HFO-1132(Z). R1224 refers to HCFO-1224yd(E), HCFO-1224yd(Z), HCFO-1224zb(E), HCFO-1224zb(Z), HCFO-1224xe(E), or HCFO-1224xe(Z). R1234 refers to HFO-1234yf, HFO-1234ze(E), or HFO-1234ze(Z). R1233 refers to HCFO-1233zd(E), HCFO-1233zd(Z), or HCFO-1233xf. R1336 refers to HFO-1336mzz(E), HFO-1336mzz(Z), HFO-1336mcy, HFO-1336mcz(E), or HFO-1336mez(Z). When these HFOs and HCFOs are used as refrigerants, the notations "HFO-" and "HCFO-" may be omitted, and the refrigerants may be referred to as "RXX," such as R1234yf.
The refrigeration apparatus of the present disclosure is preferably an air-conditioning system, a refrigerator, a freezer, a water cooler, an ice maker, a refrigerated showcase, a freezing showcase, a freezing and refrigerating unit, a refrigerating machine for freezing and refrigerating warehouses, an air-conditioning system for vehicles, a turbo refrigerating machine, or a screw refrigerating machine.
The refrigeration apparatus of the present disclosure is more preferably a household air-conditioning system, an air-conditioning system for business use, an industrial air-conditioning system, or a multi-split air-conditioning system for buildings.

Examples

The present disclosure is described below with reference to Examples; however, the present disclosure is not limited to these Examples and the like.
The GWP of the entire system was calculated using the following formula. $\begin{array}{l} GWP (t - {CO}_{2}) of entire system = (\begin{array}{l} GWP of heat - source - side \\ refrigerant \end{array}) \times (amount of heat - source - side refrigerant put in) + \\ (GWP of user - side refrigerant) \times (\begin{array}{l} amount of user - side refrigerant \\ put in \end{array}) \end{array}$
The lower these values, the less the impact on global warming.

A refrigeration apparatus was operated by circulating the user-side refrigerants and the heat-source-side refrigerants shown in Table 2 in the user-side heat transfer cycle and the heat-source-side heat transfer cycle, respectively, as shown in Fig. 1. The COP ratio and capacity ratio on the heat source side (both as ratios (%) relative to those of R410A), the burning velocities (cm/s) of the heat-source-side refrigerants and the user-side refrigerants, and the saturation vapor pressure (gauge pressure) (MPaG) of the user-side refrigerants at 25°C were determined and are shown in Tables 2 and 3.

Table 2

	Heat-source-side refrigerant	User-side refrigerant	GWP			Heat- source- side	Heat- source- side	Heat- source- side	User-side	User-side
			Heat- source- side	User side	Syetem	COP	Capacity	Burning velocity	Saturation vapor pressure (25°C)	Burning velocity
			Heat- source- side	User side	t-CO₂	vsR410A %	vsR410A %	cm/s	MPaG	cm/s
Comp. Ex.1	R32	CO2	675	1	3	102	110	6.7	6.33	0
Comp. Ex.2	R32	Water	675	0	3	102	110	6.7	-0.1	0
Ex.1	R410A	R513A	2088	631	37	100	100	0	0.61	0
Ex.2	R410A	R515B	2088	292	22	100	100	0	0.39	0
Ex.3	R410A	R1234ze(E)	2088	1	9	100	100	0	0.40	1.5
Ex.4	R410A	R1336mcy	2088	10	10	100	100	0	0.14	0
Ex.5	R410A	R1336mzz(E)	2088	10	10	100	100	0	0.09	0
Ex.6	R410A	R1224yd(Z)	2088	1	9	100	100	0	0.05	0
Ex.7	R32	R513A	675	631	30	102	110	6.7	0.61	0
Ex.8	R32	R515B	675	292	16	102	110	6.7	0.39	0
Ex.9	R32	R1234ze(E)	675	1	3	102	110	6.7	0.40	1.5
Ex.10	R32	R1336mcy	675	10	3	102	110	6.7	0.14	0
Ex.11	R32	R1336mzz(E)	675	10	3	102	110	6.7	0.09	0
Ex.12	R32	R1224yd(Z)	675	1	3	102	110	6.7	0.05	0
Ex.13	R454B	R513A	466	631	30	102	97	5.0	0.61	0
Ex.14	R454B	R515B	466	292	15	102	97	5.0	0.39	0
Ex.15	R454B	R1234ze(E)	466	1	2	102	97	5.0	0.40	1.5
Ex.16	R454B	R1336mcy	466	10	3	102	97	5.0	0.14	0
Ex.17	R454B	R1336mzz(E)	466	10	3	102	97	5.0	0.09	0
Ex.18	R454B	R1224yd(Z)	466	1	2	102	97	5.0	0.05	0
Ex.19	R452B	R513A	698	631	31	102	99	3.5	0.61	0
Ex.20	R452B	R515B	698	292	16	102	99	3.5	0.39	0
Ex.21	R452B	R1234ze(E)	698	1	3	102	99	3.5	0.40	1.5
Ex.22	R452B	R1336mcy	698	10	4	102	99	3.5	0.14	0
Ex.23	R452B	R1336mzz(E)	698	10	4	102	99	3.5	0.09	0
Ex.24	R452B	R1224yd(Z)	698	1	3	102	99	3.5	0.05	0
Ex.25	R454C	R513A	146	631	28	103	66	1.6	0.61	0
Ex.26	R454C	R515B	146	292	13	103	66	1.6	0.39	0
Ex.27	R454C	R1234ze(E)	146	1	1	103	66	1.6	0.40	1.5
Ex.28	R454C	R1336mcy	146	1	1	103	66	1.6	0.14	0
Ex.29	R454C	R1336mzz(E)	146	10	1	103	66	1.6	0.09	0
Ex.30	R454C	R1224yd(Z)	146	10	1	103	66	1.6	0.05	0

Table 3

	Heat-source-side refrigerant	User-side refrigerant		GWP		Heat- source- side	Heat- source- side	Heat- source- side	User-side	User-side
			Heat- source- side	User side	Syetem	COP	Capacity	Burning velocity	Saturation vapor pressure (25°C)	Burning velocity
			Heat- source- side	User side	t-CO₂	vsR410A %	vsR410A %	cm/s	MPaG	cm/s
Ex.31	R1132E/R1234yf=23/67	R513A	3	631	27	103	60	2.5	0.61	0
Ex.32	R1132E/R1234yf=23/67	R515B	3	292	13	103	60	2.5	0.39	0
Ex.33	R1132E/R1234yf=23/67	R1234ze(E)	3	1	0	103	60	2.5	0.40	1.5
Ex.34	R1132E/R1234yf=23/67	R1336mcy	3	1	0	103	60	2.5	0.14	0
Ex.35	R1132E/R1234yf=23/67	R1336mzz(E)	3	10	0	103	60	2.5	0.09	0
Ex.36	R1132E/R1234yf=23/67	R1224yd(Z)	3	10	0	103	60	2.5	0.05	0
Ex.37	R1132E/R1234yf=30/70	R513A	3	631	27	102	64	3.0	0.61	0
Ex.38	R1132E/R1234yf=30/70	R515B	3	292	13	102	64	3.0	0.39	0
Ex.39	R1132E/R1234yf=30/70	R1234ze(E)	3	1	0	102	64	3.0	0.40	1.5
Ex.40	R1132E/R1234yf=30/70	R1336mcy	3	1	0	102	64	3.0	0.14	0
Ex.41	R1132E/R1234yf=30/70	R1336mzz(E)	3	10	0	102	64	3.0	0.09	0
Ex.42	R1132E/R1234yf=30/70	R1224yd(Z)	3	10	0	102	64	3.0	0.05	0
Ex.43	R1132E/R1234yf=35/65	R513A	3	631	27	102	67	3.5	0.61	0
Ex.44	R1132E/R1234yf=35/65	R515B	3	292	13	102	67	3.5	0.39	0
Ex.45	R1132E/R1234yf=35/65	R1234ze(E)	3	1	0	102	67	3.5	0.40	1.5
Ex.46	R1132E/R1234yf=35/65	R1336mcy	3	1	0	102	67	3.5	0.14	0
Ex.47	R1132E/R1234yf=35/65	R1336mzz(E)	3	10	0	102	67	3.5	0.09	0
Ex.48	R1132E/R1234yf=35/65	R1224yd(Z)	3	10	0	102	67	3.5	0.05	0
Ex.49	R1132E/R1234yf/R32=15/41/44	R513A	299	631	29	101	92	7.2	0.61	0
Ex.50	R1132E/R1234yf/R32=15/41/44	R515B	299	292	14	101	92	7.2	0.39	0
Ex.51	R1132E/R1234yf/R32=15/41/44	R1234ze(E)	299	1	1	101	92	7.2	0.40	1.5
Ex.52	R1132E/R1234yf/R32=15/41/44	R1336mcy	299	1	1	101	92	7.2	0.14	0
Ex.53	R1132E/R1234yf/R32=15/41/44	R1336mzz(E)	299	10	2	101	92	7.2	0.09	0
Ex.54	R1132E/R1234yf/R32=15/41/44	R1224yd(Z)	299	10	2	101	92	7.2	0.05	0
Ex.55	R1132E/R1123/R1234yf/R32=25/25/28/22	R513A	150	631	28	98	97	7.0	0.61	0
Ex.56	R1132E/R1123/R1234yf/R32=25/25/28/22	R515B	150	292	13	98	97	7.0	0.39	0
Ex.57	R1132E/R1123/R1234yf/R32=25/25/28/22	R1234ze(E)	150	1	1	98	97	7.0	0.40	1.5
Ex.58	R1132E/R1123/R1234yf/R32=25/25/28/22	R1336mcy	150	1	1	98	97	7.0	0.14	0
Ex.59	R1132E/R1123/R1234yf/R32=25/25/28/22	R1336mzz(E)	150	10	1	98	97	7.0	0.09	0
Ex.60	R1132E/R1123/R1234yf/R32=25/25/28/22	R1224yd(Z)	150	10	1	98	97	7	0.05	0
Ex.61	R1123/R1234yf/R32=40/16/44	R513A	298	631	29	98	107	5.0	0.61	0
Ex.62	R1123/R1234yf/R32=40/16/44	R515B	298	292	14	98	107	5.0	0.39	0
Ex.63	R1123/R1234yf/R32=40/16/44	R1234ze(E)	298	1	1	98	107	5.0	0.40	1.5
Ex.64	R1123/R1234yf/R32=40/16/44	R1336mcy	298	1	1	98	107	5.0	0.14	0
Ex.65	R1123/R1234yf/R32=40/16/44	R1336mzz(E)	298	10	2	98	107	5.0	0.09	0
Ex.66	R1123/R1234yf/R32=40/16/44	R1224yd(Z)	298	10	2	98	107	5.0	0.05	0
Ex.67	R1123/R1234yf/R32=60/18.5/21.5	R513A	146	631	28	96	104	4.0	0.61	0
Ex.68	R1123/R1234yf/R32=60/18.5/21.5	R515B	146	292	13	96	104	4.0	0.39	0
Ex.69	R1123/R1234yf/R32=60/18.5/21.5	R1234ze(E)	146	1	1	96	104	4.0	0.40	1.5
Ex.70	R1123/R1234yf/R32=60/18.5/21.5	R1336mcy	146	1	1	96	104	4.0	0.14	0
Ex.71	R1123/R1234yf/R32=60/18.5/21.5	R1336mzz(E)	146	10	1	96	104	4.0	0.09	0
Ex.72	R1123/R1234yf/R32=60/18.5/21.5	R1224yd(Z)	146	10	1	96	104	4.0	0.05	0
Ex.73	R1123/R1234yf=20/80	R513A	3	631	27	102	59	2.2	0.61	0
Ex.74	R1123/R1234yf=20/80	R515B	3	292	13	102	59	2.2	0.39	0
Ex.75	R1123/R1234yf=20/80	R1234ze(E)	3	1	0	102	59	2.2	0.40	1.5
Ex.76	R1123/R1234yf=20/80	R1336mcy	3	1	0	102	59	2.2	0.14	0
Ex.77	R1123/R1234yf=20/80	R1336mzz(E)	3	10	0	102	59	2.2	0.09	0
Ex.78	R1123/R1234yf=20/80	R1224yd(Z)	3	10	0	102	59	2.2	0.05	0
Ex.79	R1123/R1234yf=30/70	R513A	3	631	27	101	66	2.6	0.61	0
Ex.80	R1123/R1234yf=30/70	R515B	3	292	13	101	66	2.6	0.39	0
Ex.81	R1123/R1234yf=30/70	R1234ze(E)	3	1	0	101	66	2.6	0.40	1.5
Ex.82	R1123/R1234yf=30/70	R1336mcy	3	1	0	101	66	2.6	0.14	0
Ex.83	R1123/R1234yf=30/70	R1336mzz(E)	3	10	0	101	66	2.6	0.09	0
Ex.84	R1123/R1234yf=30/70	R1224yd(Z)	3	10	0	101	66	2.6	0.05	0

The boiling points of the refrigerants used in the Comparative Examples and the Examples are as follows.

R410A: -51°C
R32: -52°C
R452B: -51°C
R452B: -51°C
R454C: -46°C
R513A: -29°C
R515B: -19°C
R1234ze(E): -19°C
R1336mcy: +1°C
R1224yd(Z): +14°C
R1336mzz(E): +7°C

The results show that in the refrigeration apparatus shown in Fig. 1, by using a refrigerant with a relatively high density and good performance that has a boiling point of -55°C or more and less than -30°C as the heat-source-side refrigerant, the refrigeration cycle efficiency can be maintained within a preferable range, with a COP of 100% or more and a refrigerating capacity of 60% or more, even when a refrigerant with a boiling point of -30°C or more and 25°C or less is used as the user-side refrigerant.
The results also show that by using a refrigerant with a boiling point of 25°C or less as the user-side refrigerant, its saturation vapor pressure can be made equal to or higher than atmospheric pressure. Furthermore, the results show that by using a refrigerant with a boiling point of -30°C or more as the user-side refrigerant, its pressure can be maintained at a level that does not exceed the withstanding pressure limit of the pipe.

Description of the Reference Numerals

1:: Refrigeration apparatus
10:: User-side heat transfer cycle
11:: User-side compressor
12:: User-side cascade heat exchanger
13:: User-side expansion valve
14:: User-side heat exchanger
15:: User-side liquid receiver
15a:: Fusible plug
21:: User-side high-pressure sensor
22:: User-side low-pressure sensor
23:: User-side discharge temperature sensor
30:: Heat-source-side heat transfer cycle
31:: Heat-source-side compressor
32:: Heat-source-side heat exchanger
33:: Heat-source-side expansion valve
34:: Heat-source-side cascade heat exchanger
35:: Cooling portion
40:: Cascade heat exchanger
50:: Control device

Claims

A refrigeration apparatus comprising:
a user-side heat transfer cycle configured to circulate a user-side refrigerant;

a heat-source-side heat transfer cycle configured to circulate a heat-source-side refrigerant; and

a cascade heat exchanger configured to exchange heat between the user-side refrigerant and the heat-source-side refrigerant,

the user-side refrigerant having a boiling point of -30°C or more and 25°C or less, and the heat-source-side refrigerant having a boiling point of -55°C or more and less than -30°C.
The refrigeration apparatus according to claim 1,
wherein the heat-source-side heat transfer cycle is a vapor compression refrigeration cycle comprising a heat-source-side compressor, a heat-source-side heat exchanger, a heat-source-side pressure-reducing device, and a heat-source-side cascade heat exchanger.
The refrigeration apparatus according to claim 1 or 2, wherein the user-side heat transfer cycle is a vapor compression refrigeration cycle comprising a user-side compressor, a user-side heat exchanger, a user-side pressure-reducing device, and a user-side cascade heat exchanger.
The refrigeration apparatus according to claim 1 or 2, wherein the user-side heat transfer cycle is a heat transfer cycle comprising a pump, a user-side heat exchanger, and a user-side cascade heat exchanger.
The refrigeration apparatus according to any one of claims 1 to 4, wherein flow directions of the heat-source-side refrigerant and the user-side refrigerant are in countercurrent flow in the cascade heat exchanger.
The refrigeration apparatus according to any one of claims 1 to 5, wherein the heat-source-side refrigerant has a burning velocity of 10 cm/s or less, and the user-side refrigerant has a burning velocity of 3 cm/s or less.
The refrigeration apparatus according to any one of claims 1 to 6, wherein the heat-source-side refrigerant is classified as Class 2L by ASHRAE, and the user-side refrigerant is classified as Class A1 by ASHRAE.
The refrigeration apparatus according to any one of claims 1 to 5, wherein the heat-source-side refrigerant comprises HFO-1123 and/or HFO-1132.
The refrigeration apparatus according to any one of claims 1 to 7, wherein the heat-source-side refrigerant is R32, R452B, or R454B, and the user-side refrigerant is at least one member selected from the group consisting of R513A, R515A, R515B, R1224, R1234yf, R1234ze, R1233, and R1336.
The refrigeration apparatus according to any one of claims 1 to 8, wherein the heat-source-side refrigerant comprises HFO-1132, and the user-side refrigerant is at least one member selected from the group consisting of R513A, R515A, R515B, R471A, R1224, R1234yf, R1234ze, R1233, and R1336.
The refrigeration apparatus according to any one of claims 1 to 10, which is an air-conditioning system, a refrigerator, a freezer, a water cooler, an ice maker, a refrigerated showcase, a freezing showcase, a freezing and refrigerating unit, a refrigerating machine for freezing and refrigerating warehouses, an air-conditioning system for vehicles, a turbo refrigerating machine, or a screw refrigerating machine.
The refrigeration apparatus according to any one of claims 1 to 10, which is a household air-conditioning system, an air-conditioning system for business use, an industrial air-conditioning system, or a multi-split air-conditioning system for buildings.